File: rfc9254.html

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<!DOCTYPE html>
<html lang="en" class="RFC">
<head>
<meta charset="utf-8">
<meta content="Common,Latin" name="scripts">
<meta content="initial-scale=1.0" name="viewport">
<title>RFC 9254: Encoding of Data Modeled with YANG in the Concise Binary Object Representation (CBOR)</title>
<meta content="Michel Veillette" name="author">
<meta content="Ivaylo Petrov" name="author">
<meta content="Alexander Pelov" name="author">
<meta content="Carsten Bormann" name="author">
<meta content="Michael Richardson" name="author">
<meta content="
       YANG (RFC 7950) is a data modeling language used to model configuration data,
 state data, parameters and results of Remote Procedure Call (RPC) operations or actions, and notifications. 
       This document defines encoding rules for YANG in the Concise Binary Object 
 Representation (CBOR) (RFC 8949). 
    " name="description">
<meta content="xml2rfc 3.12.10" name="generator">
<meta content="CBOR" name="keyword">
<meta content="9254" name="rfc.number">
<!-- Generator version information:
  xml2rfc 3.12.10
    Python 3.6.15
    appdirs 1.4.4
    ConfigArgParse 1.4.1
    google-i18n-address 2.4.0
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    WeasyPrint 52.5
-->
<link href="rfc9254.xml" rel="alternate" type="application/rfc+xml">
<link href="#copyright" rel="license">
<style type="text/css">/*

  NOTE: Changes at the bottom of this file overrides some earlier settings.

  Once the style has stabilized and has been adopted as an official RFC style,
  this can be consolidated so that style settings occur only in one place, but
  for now the contents of this file consists first of the initial CSS work as
  provided to the RFC Formatter (xml2rfc) work, followed by itemized and
  commented changes found necssary during the development of the v3
  formatters.

*/

/* fonts */
@import url('https://fonts.googleapis.com/css?family=Noto+Sans'); /* Sans-serif */
@import url('https://fonts.googleapis.com/css?family=Noto+Serif'); /* Serif (print) */
@import url('https://fonts.googleapis.com/css?family=Roboto+Mono'); /* Monospace */

@viewport {
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  width: extend-to-zoom;
}
@-ms-viewport {
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}
/* general and mobile first */
html {
}
body {
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  background-color: #fff;
  font-size: 14px;
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  line-height: 1.6;
  scroll-behavior: smooth;
}
.ears {
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}

/* headings */
#title, h1, h2, h3, h4, h5, h6 {
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}
#title {
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h4 {
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svg {
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.alignCenter.art-text pre {
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/* lists */
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ol ol, ul ul, ol ul, ul ol {
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ul.ulBare, li.ulBare {
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ul.compact, .ulCompact,
ol.compact, .olCompact {
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/* definition lists */
dl {
}
dl > dt {
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/* 
dl.nohang > dt {
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}
*/
dl > dd {
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  min-height: 1.3em;
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dl.compact > dd, .dlCompact > dd {
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dl > dd > dl {
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  margin-bottom: 0em;
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/* links */
a {
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}
a[href] {
  color: #22e; /* Arlen: WCAG 2019 */
}
a[href]:hover {
  background-color: #f2f2f2;
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figcaption a[href],
a[href].selfRef {
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}
/* XXX probably not this:
a.selfRef:hover {
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} */

/* Figures */
tt, code, pre, code {
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pre {
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figure {
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figure blockquote {
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figcaption {
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/* aside, blockquote */
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blockquote {
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cite {
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}

/* tables */
table {
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  border-collapse: collapse;
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}
th, td {
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  padding: 0.5em 0.75em;
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th {
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tr:nth-child(2n+1) > td {
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table caption {
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table p {
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/* pilcrow */
a.pilcrow {
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  a.pilcrow:hover {
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}

/* misc */
hr {
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}
.bcp14 {
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}

.role {
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}

/* info block */
#identifiers {
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#identifiers dt {
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#identifiers dd {
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  margin-bottom: 0;
}
/* Fix PDF info block run off issue */
@media print {
  #identifiers dd {
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}
#identifiers .authors .author {
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}
#identifiers .authors .org {
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}

/* The prepared/rendered info at the very bottom of the page */
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}
.docInfo .prepared {
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}

/* table of contents */
#toc  {
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}
nav.toc ul {
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  padding: 0;
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}
nav.toc li {
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  margin: 0.75em 0;
  padding-left: 1.2em;
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}
/* references */
.references dt {
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  font-weight: bold;
  min-width: 7em;
}
.references dd {
  margin-left: 8em;
  overflow: auto;
}

.refInstance {
  margin-bottom: 1.25em;
}

.references .ascii {
  margin-bottom: 0.25em;
}

/* index */
.index ul {
  margin: 0 0 0 1em;
  padding: 0;
  list-style: none;
}
.index ul ul {
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}
.index li {
  margin: 0;
  text-indent: -2em;
  padding-left: 2em;
  padding-bottom: 5px;
}
.indexIndex {
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}
.index a {
  font-weight: 700;
}
/* make the index two-column on all but the smallest screens */
@media (min-width: 600px) {
  .index ul {
    -moz-column-count: 2;
    -moz-column-gap: 20px;
  }
  .index ul ul {
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}

/* authors */
address.vcard {
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}

address.vcard .nameRole {
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}
address.vcard .label {
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address.vcard .type {
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.alternative-contact {
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}
hr.addr {
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  color: #ddd;
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}

/* temporary notes */
.rfcEditorRemove::before {
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  right: 0.2em;
  padding: 0.2em;
  content: "The RFC Editor will remove this note";
  color: #9e2a00; /* Arlen: WCAG 2019 */
  background-color: #ffd; /* Arlen: WCAG 2019 */
}
.rfcEditorRemove {
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}
.cref {
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}
.crefSource {
  font-style: italic;
}
/* alternative layout for smaller screens */
@media screen and (max-width: 1023px) {
  body {
    padding-top: 2em;
  }
  #title {
    padding: 1em 0;
  }
  h1 {
    font-size: 24px;
  }
  h2 {
    font-size: 20px;
    margin-top: -18px;  /* provide offset for in-page anchors */
    padding-top: 38px;
  }
  #identifiers dd {
    max-width: 60%;
  }
  #toc {
    position: fixed;
    z-index: 2;
    top: 0;
    right: 0;
    padding: 0;
    margin: 0;
    background-color: inherit;
    border-bottom: 1px solid #ccc;
  }
  #toc h2 {
    margin: -1px 0 0 0;
    padding: 4px 0 4px 6px;
    padding-right: 1em;
    min-width: 190px;
    font-size: 1.1em;
    text-align: right;
    background-color: #444;
    color: white;
    cursor: pointer;
  }
  #toc h2::before { /* css hamburger */
    float: right;
    position: relative;
    width: 1em;
    height: 1px;
    left: -164px;
    margin: 6px 0 0 0;
    background: white none repeat scroll 0 0;
    box-shadow: 0 4px 0 0 white, 0 8px 0 0 white;
    content: "";
  }
  #toc nav {
    display: none;
    padding: 0.5em 1em 1em;
    overflow: auto;
    height: calc(100vh - 48px);
    border-left: 1px solid #ddd;
  }
}

/* alternative layout for wide screens */
@media screen and (min-width: 1024px) {
  body {
    max-width: 724px;
    margin: 42px auto;
    padding-left: 1.5em;
    padding-right: 29em;
  }
  #toc {
    position: fixed;
    top: 42px;
    right: 42px;
    width: 25%;
    margin: 0;
    padding: 0 1em;
    z-index: 1;
  }
  #toc h2 {
    border-top: none;
    border-bottom: 1px solid #ddd;
    font-size: 1em;
    font-weight: normal;
    margin: 0;
    padding: 0.25em 1em 1em 0;
  }
  #toc nav {
    display: block;
    height: calc(90vh - 84px);
    bottom: 0;
    padding: 0.5em 0 0;
    overflow: auto;
  }
  img { /* future proofing */
    max-width: 100%;
    height: auto;
  }
}

/* pagination */
@media print {
  body {

    width: 100%;
  }
  p {
    orphans: 3;
    widows: 3;
  }
  #n-copyright-notice {
    border-bottom: none;
  }
  #toc, #n-introduction {
    page-break-before: always;
  }
  #toc {
    border-top: none;
    padding-top: 0;
  }
  figure, pre {
    page-break-inside: avoid;
  }
  figure {
    overflow: scroll;
  }
  pre.breakable {
    break-inside: auto;
  }
  h1, h2, h3, h4, h5, h6 {
    page-break-after: avoid;
  }
  h2+*, h3+*, h4+*, h5+*, h6+* {
    page-break-before: avoid;
  }
  pre {
    white-space: pre-wrap;
    word-wrap: break-word;
    font-size: 10pt;
  }
  table {
    border: 1px solid #ddd;
  }
  td {
    border-top: 1px solid #ddd;
  }
}

/* This is commented out here, as the string-set: doesn't
   pass W3C validation currently */
/*
.ears thead .left {
  string-set: ears-top-left content();
}

.ears thead .center {
  string-set: ears-top-center content();
}

.ears thead .right {
  string-set: ears-top-right content();
}

.ears tfoot .left {
  string-set: ears-bottom-left content();
}

.ears tfoot .center {
  string-set: ears-bottom-center content();
}

.ears tfoot .right {
  string-set: ears-bottom-right content();
}
*/

@page :first {
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    border: none;
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  @top-center {
    content: normal;
    border: none;
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  @top-right {
    content: normal;
    border: none;
  }
}

@page {
  size: A4;
  margin-bottom: 45mm;
  padding-top: 20px;
  /* The follwing is commented out here, but set appropriately by in code, as
     the content depends on the document */
  /*
  @top-left {
    content: 'Internet-Draft';
    vertical-align: bottom;
    border-bottom: solid 1px #ccc;
  }
  @top-left {
    content: string(ears-top-left);
    vertical-align: bottom;
    border-bottom: solid 1px #ccc;
  }
  @top-center {
    content: string(ears-top-center);
    vertical-align: bottom;
    border-bottom: solid 1px #ccc;
  }
  @top-right {
    content: string(ears-top-right);
    vertical-align: bottom;
    border-bottom: solid 1px #ccc;
  }
  @bottom-left {
    content: string(ears-bottom-left);
    vertical-align: top;
    border-top: solid 1px #ccc;
  }
  @bottom-center {
    content: string(ears-bottom-center);
    vertical-align: top;
    border-top: solid 1px #ccc;
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  @bottom-right {
      content: '[Page ' counter(page) ']';
      vertical-align: top;
      border-top: solid 1px #ccc;
  }
  */

}

/* Changes introduced to fix issues found during implementation */
/* Make sure links are clickable even if overlapped by following H* */
a {
  z-index: 2;
}
/* Separate body from document info even without intervening H1 */
section {
  clear: both;
}


/* Top align author divs, to avoid names without organization dropping level with org names */
.author {
  vertical-align: top;
}

/* Leave room in document info to show Internet-Draft on one line */
#identifiers dt {
  width: 8em;
}

/* Don't waste quite as much whitespace between label and value in doc info */
#identifiers dd {
  margin-left: 1em;
}

/* Give floating toc a background color (needed when it's a div inside section */
#toc {
  background-color: white;
}

/* Make the collapsed ToC header render white on gray also when it's a link */
@media screen and (max-width: 1023px) {
  #toc h2 a,
  #toc h2 a:link,
  #toc h2 a:focus,
  #toc h2 a:hover,
  #toc a.toplink,
  #toc a.toplink:hover {
    color: white;
    background-color: #444;
    text-decoration: none;
  }
}

/* Give the bottom of the ToC some whitespace */
@media screen and (min-width: 1024px) {
  #toc {
    padding: 0 0 1em 1em;
  }
}

/* Style section numbers with more space between number and title */
.section-number {
  padding-right: 0.5em;
}

/* prevent monospace from becoming overly large */
tt, code, pre, code {
  font-size: 95%;
}

/* Fix the height/width aspect for ascii art*/
pre.sourcecode,
.art-text pre {
  line-height: 1.12;
}


/* Add styling for a link in the ToC that points to the top of the document */
a.toplink {
  float: right;
  margin-right: 0.5em;
}

/* Fix the dl styling to match the RFC 7992 attributes */
dl > dt,
dl.dlParallel > dt {
  float: left;
  margin-right: 1em;
}
dl.dlNewline > dt {
  float: none;
}

/* Provide styling for table cell text alignment */
table td.text-left,
table th.text-left {
  text-align: left;
}
table td.text-center,
table th.text-center {
  text-align: center;
}
table td.text-right,
table th.text-right {
  text-align: right;
}

/* Make the alternative author contact informatio look less like just another
   author, and group it closer with the primary author contact information */
.alternative-contact {
  margin: 0.5em 0 0.25em 0;
}
address .non-ascii {
  margin: 0 0 0 2em;
}

/* With it being possible to set tables with alignment
  left, center, and right, { width: 100%; } does not make sense */
table {
  width: auto;
}

/* Avoid reference text that sits in a block with very wide left margin,
   because of a long floating dt label.*/
.references dd {
  overflow: visible;
}

/* Control caption placement */
caption {
  caption-side: bottom;
}

/* Limit the width of the author address vcard, so names in right-to-left
   script don't end up on the other side of the page. */

address.vcard {
  max-width: 30em;
  margin-right: auto;
}

/* For address alignment dependent on LTR or RTL scripts */
address div.left {
  text-align: left;
}
address div.right {
  text-align: right;
}

/* Provide table alignment support.  We can't use the alignX classes above
   since they do unwanted things with caption and other styling. */
table.right {
 margin-left: auto;
 margin-right: 0;
}
table.center {
 margin-left: auto;
 margin-right: auto;
}
table.left {
 margin-left: 0;
 margin-right: auto;
}

/* Give the table caption label the same styling as the figcaption */
caption a[href] {
  color: #222;
}

@media print {
  .toplink {
    display: none;
  }

  /* avoid overwriting the top border line with the ToC header */
  #toc {
    padding-top: 1px;
  }

  /* Avoid page breaks inside dl and author address entries */
  .vcard {
    page-break-inside: avoid;
  }

}
/* Tweak the bcp14 keyword presentation */
.bcp14 {
  font-variant: small-caps;
  font-weight: bold;
  font-size: 0.9em;
}
/* Tweak the invisible space above H* in order not to overlay links in text above */
 h2 {
  margin-top: -18px;  /* provide offset for in-page anchors */
  padding-top: 31px;
 }
 h3 {
  margin-top: -18px;  /* provide offset for in-page anchors */
  padding-top: 24px;
 }
 h4 {
  margin-top: -18px;  /* provide offset for in-page anchors */
  padding-top: 24px;
 }
/* Float artwork pilcrow to the right */
@media screen {
  .artwork a.pilcrow {
    display: block;
    line-height: 0.7;
    margin-top: 0.15em;
  }
}
/* Make pilcrows on dd visible */
@media screen {
  dd:hover > a.pilcrow {
    visibility: visible;
  }
}
/* Make the placement of figcaption match that of a table's caption
   by removing the figure's added bottom margin */
.alignLeft.art-text,
.alignCenter.art-text,
.alignRight.art-text {
   margin-bottom: 0;
}
.alignLeft,
.alignCenter,
.alignRight {
  margin: 1em 0 0 0;
}
/* In print, the pilcrow won't show on hover, so prevent it from taking up space,
   possibly even requiring a new line */
@media print {
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<link href="https://dx.doi.org/10.17487/rfc9254" rel="alternate">
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<table class="ears">
<thead><tr>
<td class="left">RFC 9254</td>
<td class="center">CBOR Encoding of Data Modeled with YANG</td>
<td class="right">July 2022</td>
</tr></thead>
<tfoot><tr>
<td class="left">Veillette, et al.</td>
<td class="center">Standards Track</td>
<td class="right">[Page]</td>
</tr></tfoot>
</table>
<div id="external-metadata" class="document-information"></div>
<div id="internal-metadata" class="document-information">
<dl id="identifiers">
<dt class="label-stream">Stream:</dt>
<dd class="stream">Internet Engineering Task Force (IETF)</dd>
<dt class="label-rfc">RFC:</dt>
<dd class="rfc"><a href="https://www.rfc-editor.org/rfc/rfc9254" class="eref">9254</a></dd>
<dt class="label-category">Category:</dt>
<dd class="category">Standards Track</dd>
<dt class="label-published">Published:</dt>
<dd class="published">
<time datetime="2022-07" class="published">July 2022</time>
    </dd>
<dt class="label-issn">ISSN:</dt>
<dd class="issn">2070-1721</dd>
<dt class="label-authors">Authors:</dt>
<dd class="authors">
<div class="author">
      <div class="author-name">M. Veillette, <span class="editor">Ed.</span>
</div>
<div class="org">Trilliant Networks Inc.</div>
</div>
<div class="author">
      <div class="author-name">I. Petrov, <span class="editor">Ed.</span>
</div>
<div class="org">Google Switzerland GmbH</div>
</div>
<div class="author">
      <div class="author-name">A. Pelov</div>
<div class="org">Acklio</div>
</div>
<div class="author">
      <div class="author-name">C. Bormann</div>
<div class="org">Universität Bremen TZI</div>
</div>
<div class="author">
      <div class="author-name">M. Richardson</div>
<div class="org">Sandelman Software Works</div>
</div>
</dd>
</dl>
</div>
<h1 id="rfcnum">RFC 9254</h1>
<h1 id="title">Encoding of Data Modeled with YANG in the Concise Binary Object Representation (CBOR)</h1>
<section id="section-abstract">
      <h2 id="abstract"><a href="#abstract" class="selfRef">Abstract</a></h2>
<p id="section-abstract-1">YANG (RFC 7950) is a data modeling language used to model configuration data,
 state data, parameters and results of Remote Procedure Call (RPC) operations or actions, and notifications.<a href="#section-abstract-1" class="pilcrow">¶</a></p>
<p id="section-abstract-2">This document defines encoding rules for YANG in the Concise Binary Object 
 Representation (CBOR) (RFC 8949).<a href="#section-abstract-2" class="pilcrow">¶</a></p>
</section>
<div id="status-of-memo">
<section id="section-boilerplate.1">
        <h2 id="name-status-of-this-memo">
<a href="#name-status-of-this-memo" class="section-name selfRef">Status of This Memo</a>
        </h2>
<p id="section-boilerplate.1-1">
            This is an Internet Standards Track document.<a href="#section-boilerplate.1-1" class="pilcrow">¶</a></p>
<p id="section-boilerplate.1-2">
            This document is a product of the Internet Engineering Task Force
            (IETF).  It represents the consensus of the IETF community.  It has
            received public review and has been approved for publication by
            the Internet Engineering Steering Group (IESG).  Further
            information on Internet Standards is available in Section 2 of 
            RFC 7841.<a href="#section-boilerplate.1-2" class="pilcrow">¶</a></p>
<p id="section-boilerplate.1-3">
            Information about the current status of this document, any
            errata, and how to provide feedback on it may be obtained at
            <span><a href="https://www.rfc-editor.org/info/rfc9254">https://www.rfc-editor.org/info/rfc9254</a></span>.<a href="#section-boilerplate.1-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="copyright">
<section id="section-boilerplate.2">
        <h2 id="name-copyright-notice">
<a href="#name-copyright-notice" class="section-name selfRef">Copyright Notice</a>
        </h2>
<p id="section-boilerplate.2-1">
            Copyright (c) 2022 IETF Trust and the persons identified as the
            document authors. All rights reserved.<a href="#section-boilerplate.2-1" class="pilcrow">¶</a></p>
<p id="section-boilerplate.2-2">
            This document is subject to BCP 78 and the IETF Trust's Legal
            Provisions Relating to IETF Documents
            (<span><a href="https://trustee.ietf.org/license-info">https://trustee.ietf.org/license-info</a></span>) in effect on the date of
            publication of this document. Please review these documents
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            document must include Revised BSD License text as described in
            Section 4.e of the Trust Legal Provisions and are provided without
            warranty as described in the Revised BSD License.<a href="#section-boilerplate.2-2" class="pilcrow">¶</a></p>
</section>
</div>
<div id="toc">
<section id="section-toc.1">
        <a href="#" onclick="scroll(0,0)" class="toplink">▲</a><h2 id="name-table-of-contents">
<a href="#name-table-of-contents" class="section-name selfRef">Table of Contents</a>
        </h2>
<nav class="toc"><ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.1">
            <p id="section-toc.1-1.1.1" class="keepWithNext"><a href="#section-1" class="xref">1</a>.  <a href="#name-introduction" class="xref">Introduction</a></p>
</li>
          <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.2">
            <p id="section-toc.1-1.2.1" class="keepWithNext"><a href="#section-2" class="xref">2</a>.  <a href="#name-terminology-and-notation" class="xref">Terminology and Notation</a></p>
</li>
          <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.3">
            <p id="section-toc.1-1.3.1"><a href="#section-3" class="xref">3</a>.  <a href="#name-properties-of-the-cbor-enco" class="xref">Properties of the CBOR Encoding</a></p>
<ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.3.2.1">
                <p id="section-toc.1-1.3.2.1.1" class="keepWithNext"><a href="#section-3.1" class="xref">3.1</a>.  <a href="#name-cbor-diagnostic-notation" class="xref">CBOR Diagnostic Notation</a></p>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.3.2.2">
                <p id="section-toc.1-1.3.2.2.1"><a href="#section-3.2" class="xref">3.2</a>.  <a href="#name-yang-schema-item-identifier" class="xref">YANG Schema Item iDentifier</a></p>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.3.2.3">
                <p id="section-toc.1-1.3.2.3.1"><a href="#section-3.3" class="xref">3.3</a>.  <a href="#name-name" class="xref">Name</a></p>
</li>
            </ul>
</li>
          <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.4">
            <p id="section-toc.1-1.4.1"><a href="#section-4" class="xref">4</a>.  <a href="#name-encoding-of-representation-" class="xref">Encoding of Representation Nodes</a></p>
<ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.4.2.1">
                <p id="section-toc.1-1.4.2.1.1"><a href="#section-4.1" class="xref">4.1</a>.  <a href="#name-the-leaf" class="xref">The 'leaf'</a></p>
<ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.4.2.1.2.1">
                    <p id="section-toc.1-1.4.2.1.2.1.1"><a href="#section-4.1.1" class="xref">4.1.1</a>.  <a href="#name-using-sids-in-keys" class="xref">Using SIDs in Keys</a></p>
</li>
                  <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.4.2.1.2.2">
                    <p id="section-toc.1-1.4.2.1.2.2.1"><a href="#section-4.1.2" class="xref">4.1.2</a>.  <a href="#name-using-names-in-keys" class="xref">Using Names in Keys</a></p>
</li>
                </ul>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.4.2.2">
                <p id="section-toc.1-1.4.2.2.1"><a href="#section-4.2" class="xref">4.2</a>.  <a href="#name-the-container-and-other-nod" class="xref">The 'container' and Other Nodes from the Data Tree</a></p>
<ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.4.2.2.2.1">
                    <p id="section-toc.1-1.4.2.2.2.1.1"><a href="#section-4.2.1" class="xref">4.2.1</a>.  <a href="#name-using-sids-in-keys-2" class="xref">Using SIDs in Keys</a></p>
</li>
                  <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.4.2.2.2.2">
                    <p id="section-toc.1-1.4.2.2.2.2.1"><a href="#section-4.2.2" class="xref">4.2.2</a>.  <a href="#name-using-names-in-keys-2" class="xref">Using Names in Keys</a></p>
</li>
                </ul>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.4.2.3">
                <p id="section-toc.1-1.4.2.3.1"><a href="#section-4.3" class="xref">4.3</a>.  <a href="#name-the-leaf-list" class="xref">The 'leaf-list'</a></p>
<ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.4.2.3.2.1">
                    <p id="section-toc.1-1.4.2.3.2.1.1"><a href="#section-4.3.1" class="xref">4.3.1</a>.  <a href="#name-using-sids-in-keys-3" class="xref">Using SIDs in Keys</a></p>
</li>
                  <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.4.2.3.2.2">
                    <p id="section-toc.1-1.4.2.3.2.2.1"><a href="#section-4.3.2" class="xref">4.3.2</a>.  <a href="#name-using-names-in-keys-3" class="xref">Using Names in Keys</a></p>
</li>
                </ul>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.4.2.4">
                <p id="section-toc.1-1.4.2.4.1"><a href="#section-4.4" class="xref">4.4</a>.  <a href="#name-the-list-and-the-list-entri" class="xref">The 'list' and the 'list' Entries</a></p>
<ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.4.2.4.2.1">
                    <p id="section-toc.1-1.4.2.4.2.1.1"><a href="#section-4.4.1" class="xref">4.4.1</a>.  <a href="#name-using-sids-in-keys-4" class="xref">Using SIDs in Keys</a></p>
</li>
                  <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.4.2.4.2.2">
                    <p id="section-toc.1-1.4.2.4.2.2.1"><a href="#section-4.4.2" class="xref">4.4.2</a>.  <a href="#name-using-names-in-keys-4" class="xref">Using Names in Keys</a></p>
</li>
                </ul>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.4.2.5">
                <p id="section-toc.1-1.4.2.5.1"><a href="#section-4.5" class="xref">4.5</a>.  <a href="#name-the-anydata" class="xref">The 'anydata'</a></p>
<ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.4.2.5.2.1">
                    <p id="section-toc.1-1.4.2.5.2.1.1"><a href="#section-4.5.1" class="xref">4.5.1</a>.  <a href="#name-using-sids-in-keys-5" class="xref">Using SIDs in Keys</a></p>
</li>
                  <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.4.2.5.2.2">
                    <p id="section-toc.1-1.4.2.5.2.2.1"><a href="#section-4.5.2" class="xref">4.5.2</a>.  <a href="#name-using-names-in-keys-5" class="xref">Using Names in Keys</a></p>
</li>
                </ul>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.4.2.6">
                <p id="section-toc.1-1.4.2.6.1"><a href="#section-4.6" class="xref">4.6</a>.  <a href="#name-the-anyxml" class="xref">The 'anyxml'</a></p>
<ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.4.2.6.2.1">
                    <p id="section-toc.1-1.4.2.6.2.1.1"><a href="#section-4.6.1" class="xref">4.6.1</a>.  <a href="#name-using-sids-in-keys-6" class="xref">Using SIDs in Keys</a></p>
</li>
                  <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.4.2.6.2.2">
                    <p id="section-toc.1-1.4.2.6.2.2.1"><a href="#section-4.6.2" class="xref">4.6.2</a>.  <a href="#name-using-names-in-keys-6" class="xref">Using Names in Keys</a></p>
</li>
                </ul>
</li>
            </ul>
</li>
          <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.5">
            <p id="section-toc.1-1.5.1"><a href="#section-5" class="xref">5</a>.  <a href="#name-encoding-of-the-yang-data-e" class="xref">Encoding of the 'yang-data' Extension</a></p>
<ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.5.2.1">
                <p id="section-toc.1-1.5.2.1.1"><a href="#section-5.1" class="xref">5.1</a>.  <a href="#name-using-sids-in-keys-7" class="xref">Using SIDs in Keys</a></p>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.5.2.2">
                <p id="section-toc.1-1.5.2.2.1"><a href="#section-5.2" class="xref">5.2</a>.  <a href="#name-using-names-in-keys-7" class="xref">Using Names in Keys</a></p>
</li>
            </ul>
</li>
          <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.6">
            <p id="section-toc.1-1.6.1"><a href="#section-6" class="xref">6</a>.  <a href="#name-representing-yang-data-type" class="xref">Representing YANG Data Types in CBOR</a></p>
<ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.6.2.1">
                <p id="section-toc.1-1.6.2.1.1"><a href="#section-6.1" class="xref">6.1</a>.  <a href="#name-the-unsigned-integer-types" class="xref">The Unsigned Integer Types</a></p>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.6.2.2">
                <p id="section-toc.1-1.6.2.2.1"><a href="#section-6.2" class="xref">6.2</a>.  <a href="#name-the-integer-types" class="xref">The Integer Types</a></p>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.6.2.3">
                <p id="section-toc.1-1.6.2.3.1"><a href="#section-6.3" class="xref">6.3</a>.  <a href="#name-the-decimal64-type" class="xref">The 'decimal64' Type</a></p>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.6.2.4">
                <p id="section-toc.1-1.6.2.4.1"><a href="#section-6.4" class="xref">6.4</a>.  <a href="#name-the-string-type" class="xref">The 'string' Type</a></p>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.6.2.5">
                <p id="section-toc.1-1.6.2.5.1"><a href="#section-6.5" class="xref">6.5</a>.  <a href="#name-the-boolean-type" class="xref">The 'boolean' Type</a></p>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.6.2.6">
                <p id="section-toc.1-1.6.2.6.1"><a href="#section-6.6" class="xref">6.6</a>.  <a href="#name-the-enumeration-type" class="xref">The 'enumeration' Type</a></p>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.6.2.7">
                <p id="section-toc.1-1.6.2.7.1"><a href="#section-6.7" class="xref">6.7</a>.  <a href="#name-the-bits-type" class="xref">The 'bits' Type</a></p>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.6.2.8">
                <p id="section-toc.1-1.6.2.8.1"><a href="#section-6.8" class="xref">6.8</a>.  <a href="#name-the-binary-type" class="xref">The 'binary' Type</a></p>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.6.2.9">
                <p id="section-toc.1-1.6.2.9.1"><a href="#section-6.9" class="xref">6.9</a>.  <a href="#name-the-leafref-type" class="xref">The 'leafref' Type</a></p>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.6.2.10">
                <p id="section-toc.1-1.6.2.10.1"><a href="#section-6.10" class="xref">6.10</a>. <a href="#name-the-identityref-type" class="xref">The 'identityref' Type</a></p>
<ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.6.2.10.2.1">
                    <p id="section-toc.1-1.6.2.10.2.1.1"><a href="#section-6.10.1" class="xref">6.10.1</a>.  <a href="#name-sids-as-identityref" class="xref">SIDs as 'identityref'</a></p>
</li>
                  <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.6.2.10.2.2">
                    <p id="section-toc.1-1.6.2.10.2.2.1"><a href="#section-6.10.2" class="xref">6.10.2</a>.  <a href="#name-name-as-identityref" class="xref">Name as 'identityref'</a></p>
</li>
                </ul>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.6.2.11">
                <p id="section-toc.1-1.6.2.11.1"><a href="#section-6.11" class="xref">6.11</a>. <a href="#name-the-empty-type" class="xref">The 'empty' Type</a></p>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.6.2.12">
                <p id="section-toc.1-1.6.2.12.1"><a href="#section-6.12" class="xref">6.12</a>. <a href="#name-the-union-type" class="xref">The 'union' Type</a></p>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.6.2.13">
                <p id="section-toc.1-1.6.2.13.1"><a href="#section-6.13" class="xref">6.13</a>. <a href="#name-the-instance-identifier-typ" class="xref">The 'instance-identifier' Type</a></p>
<ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.6.2.13.2.1">
                    <p id="section-toc.1-1.6.2.13.2.1.1"><a href="#section-6.13.1" class="xref">6.13.1</a>.  <a href="#name-sids-as-instance-identifier" class="xref">SIDs as 'instance-identifier'</a></p>
</li>
                  <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.6.2.13.2.2">
                    <p id="section-toc.1-1.6.2.13.2.2.1"><a href="#section-6.13.2" class="xref">6.13.2</a>.  <a href="#name-names-as-instance-identifie" class="xref">Names as 'instance-identifier'</a></p>
</li>
                </ul>
</li>
            </ul>
</li>
          <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.7">
            <p id="section-toc.1-1.7.1"><a href="#section-7" class="xref">7</a>.  <a href="#name-content-types" class="xref">Content-Types</a></p>
</li>
          <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.8">
            <p id="section-toc.1-1.8.1"><a href="#section-8" class="xref">8</a>.  <a href="#name-security-considerations" class="xref">Security Considerations</a></p>
</li>
          <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.9">
            <p id="section-toc.1-1.9.1"><a href="#section-9" class="xref">9</a>.  <a href="#name-iana-considerations" class="xref">IANA Considerations</a></p>
<ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.9.2.1">
                <p id="section-toc.1-1.9.2.1.1"><a href="#section-9.1" class="xref">9.1</a>.  <a href="#name-media-types-registry" class="xref">Media Types Registry</a></p>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.9.2.2">
                <p id="section-toc.1-1.9.2.2.1"><a href="#section-9.2" class="xref">9.2</a>.  <a href="#name-coap-content-formats-regist" class="xref">CoAP Content-Formats Registry</a></p>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.9.2.3">
                <p id="section-toc.1-1.9.2.3.1"><a href="#section-9.3" class="xref">9.3</a>.  <a href="#name-cbor-tags-registry" class="xref">CBOR Tags Registry</a></p>
</li>
            </ul>
</li>
          <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.10">
            <p id="section-toc.1-1.10.1"><a href="#section-10" class="xref">10</a>. <a href="#name-references" class="xref">References</a></p>
<ul class="compact toc ulBare ulEmpty">
<li class="compact toc ulBare ulEmpty" id="section-toc.1-1.10.2.1">
                <p id="section-toc.1-1.10.2.1.1"><a href="#section-10.1" class="xref">10.1</a>.  <a href="#name-normative-references" class="xref">Normative References</a></p>
</li>
              <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.10.2.2">
                <p id="section-toc.1-1.10.2.2.1"><a href="#section-10.2" class="xref">10.2</a>.  <a href="#name-informative-references" class="xref">Informative References</a></p>
</li>
            </ul>
</li>
          <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.11">
            <p id="section-toc.1-1.11.1"><a href="#appendix-A" class="xref"></a><a href="#name-acknowledgments" class="xref">Acknowledgments</a></p>
</li>
          <li class="compact toc ulBare ulEmpty" id="section-toc.1-1.12">
            <p id="section-toc.1-1.12.1"><a href="#appendix-B" class="xref"></a><a href="#name-authors-addresses" class="xref">Authors' Addresses</a></p>
</li>
        </ul>
</nav>
</section>
</div>
<div id="introduction">
<section id="section-1">
      <h2 id="name-introduction">
<a href="#section-1" class="section-number selfRef">1. </a><a href="#name-introduction" class="section-name selfRef">Introduction</a>
      </h2>
<p id="section-1-1">The specification of the YANG 1.1 data modeling language <span>[<a href="#RFC7950" class="xref">RFC7950</a>]</span> defines an XML encoding for data instances, i.e., contents of configuration datastores, state data, RPC inputs and outputs, action inputs and outputs, and event notifications.<a href="#section-1-1" class="pilcrow">¶</a></p>
<p id="section-1-2">An additional set of encoding rules has been defined in <span>[<a href="#RFC7951" class="xref">RFC7951</a>]</span> based on
      "The JavaScript Object Notation (JSON) Data Interchange Format" <span>[<a href="#RFC8259" class="xref">RFC8259</a>]</span>.<a href="#section-1-2" class="pilcrow">¶</a></p>
<p id="section-1-3">The aim of this document is to define a set of encoding rules for the Concise Binary Object Representation (CBOR) <span>[<a href="#RFC8949" class="xref">RFC8949</a>]</span>, collectively called "YANG-CBOR". The resulting encoding is more compact compared to XML and JSON and more suitable for constrained nodes and/or constrained networks, as defined by <span>[<a href="#RFC7228" class="xref">RFC7228</a>]</span>.<a href="#section-1-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="terminology-and-notation">
<section id="section-2">
      <h2 id="name-terminology-and-notation">
<a href="#section-2" class="section-number selfRef">2. </a><a href="#name-terminology-and-notation" class="section-name selfRef">Terminology and Notation</a>
      </h2>
<p id="section-2-1">
    The key words "<span class="bcp14">MUST</span>", "<span class="bcp14">MUST NOT</span>", "<span class="bcp14">REQUIRED</span>", "<span class="bcp14">SHALL</span>", "<span class="bcp14">SHALL NOT</span>", "<span class="bcp14">SHOULD</span>", "<span class="bcp14">SHOULD NOT</span>", "<span class="bcp14">RECOMMENDED</span>", "<span class="bcp14">NOT RECOMMENDED</span>",
    "<span class="bcp14">MAY</span>", and "<span class="bcp14">OPTIONAL</span>" in this document are to be interpreted as
    described in BCP 14 <span>[<a href="#RFC2119" class="xref">RFC2119</a>]</span> <span>[<a href="#RFC8174" class="xref">RFC8174</a>]</span> 
    when, and only when, they appear in all capitals, as shown here.<a href="#section-2-1" class="pilcrow">¶</a></p>
<p id="section-2-2">SID values (and the SID deltas computed from them) shown in the examples are example values; these examples do not allocate the SIDs shown for specific items in the modules.<a href="#section-2-2" class="pilcrow">¶</a></p>
<p id="section-2-3">The following terms are defined in <span>[<a href="#RFC7950" class="xref">RFC7950</a>]</span>:<a href="#section-2-3" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-2-4.1">action<a href="#section-2-4.1" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-2-4.2">anydata<a href="#section-2-4.2" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-2-4.3">anyxml<a href="#section-2-4.3" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-2-4.4">data node<a href="#section-2-4.4" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-2-4.5">data tree<a href="#section-2-4.5" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-2-4.6">datastore<a href="#section-2-4.6" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-2-4.7">feature<a href="#section-2-4.7" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-2-4.8">identity<a href="#section-2-4.8" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-2-4.9">module<a href="#section-2-4.9" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-2-4.10">notification<a href="#section-2-4.10" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-2-4.11">RPC<a href="#section-2-4.11" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-2-4.12">schema node<a href="#section-2-4.12" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-2-4.13">submodule<a href="#section-2-4.13" class="pilcrow">¶</a>
</li>
      </ul>
<p id="section-2-5">The following term is defined in <span>[<a href="#RFC8040" class="xref">RFC8040</a>]</span>:<a href="#section-2-5" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-2-6.1">yang-data extension<a href="#section-2-6.1" class="pilcrow">¶</a>
</li>
      </ul>
<p id="section-2-7">The following term is defined in <span>[<a href="#RFC8791" class="xref">RFC8791</a>]</span>:<a href="#section-2-7" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-2-8.1">YANG data structure<a href="#section-2-8.1" class="pilcrow">¶</a>
</li>
      </ul>
<p id="section-2-9">This specification also makes use of the following terminology:<a href="#section-2-9" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlNewline" id="section-2-10">
        <dt id="section-2-10.1">YANG Schema Item iDentifier (or "YANG SID" or simply "SID"):</dt>
        <dd style="margin-left: 1.5em" id="section-2-10.2"> 63-bit unsigned integer used to identify different YANG items.<a href="#section-2-10.2" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-10.3">delta:</dt>
        <dd style="margin-left: 1.5em" id="section-2-10.4"> Difference between the current YANG SID and a reference YANG SID. A reference YANG SID is defined for each context for which deltas are used.<a href="#section-2-10.4" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-10.5">absolute SID:</dt>
        <dd style="margin-left: 1.5em" id="section-2-10.6">A YANG SID that is not encoded as a delta.  This is usually
called out explicitly only in positions where normally a delta would
be found.<a href="#section-2-10.6" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-10.7">representation tree:</dt>
        <dd style="margin-left: 1.5em" id="section-2-10.8"> A YANG data tree, possibly enclosed by a
representation of a schema node, such as a YANG data structure, a notification, an RPC, or
an action.<a href="#section-2-10.8" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-10.9">representation node:</dt>
        <dd style="margin-left: 1.5em" id="section-2-10.10"> A node in a representation tree, i.e., a data
tree node, or a representation of a schema node, such as a YANG data structure, a
notification, an RPC, or an action.<a href="#section-2-10.10" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-10.11">item:</dt>
        <dd style="margin-left: 1.5em" id="section-2-10.12"> A schema node, an identity, a module, or a feature defined using the YANG modeling language.<a href="#section-2-10.12" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-10.13">list entry:</dt>
        <dd style="margin-left: 1.5em" id="section-2-10.14"> The data associated with a single entry of a list (see
 <span><a href="https://www.rfc-editor.org/rfc/rfc7950#section-7.8" class="relref">Section 7.8</a> of [<a href="#RFC7950" class="xref">RFC7950</a>]</span>).<a href="#section-2-10.14" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-10.15">container-like instance:</dt>
        <dd style="margin-left: 1.5em" id="section-2-10.16"> An instance of a container,
 a YANG data structure, notification contents, RPC input, RPC output,
 action input, or action output (<a href="#container" class="xref">Section 4.2</a>); a list entry in a list (<a href="#list" class="xref">Section 4.4</a>); or an anydata node (<a href="#the-anydata" class="xref">Section 4.5</a>).<a href="#section-2-10.16" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-2-10.17">parent (of a representation node):</dt>
        <dd style="margin-left: 1.5em" id="section-2-10.18"> The schema node of the closest
enclosing representation node in which a given representation node
is defined.<a href="#section-2-10.18" class="pilcrow">¶</a>
</dd>
      <dd class="break"></dd>
</dl>
</section>
</div>
<div id="properties-of-cbor-encoding">
<section id="section-3">
      <h2 id="name-properties-of-the-cbor-enco">
<a href="#section-3" class="section-number selfRef">3. </a><a href="#name-properties-of-the-cbor-enco" class="section-name selfRef">Properties of the CBOR Encoding</a>
      </h2>
<p id="section-3-1">This document defines CBOR encoding rules for YANG data trees and their subtrees.<a href="#section-3-1" class="pilcrow">¶</a></p>
<p id="section-3-2">A YANG data tree can be enclosed by a representation of a schema node, such as a YANG data structure, a notification, an RPC, or an action; this is called a representation tree.  The data tree nodes and the enclosing schema node representation, if any, are collectively called the representation nodes.<a href="#section-3-2" class="pilcrow">¶</a></p>
<p id="section-3-3">A representation node, such as a container, list entry, YANG data structure, notification, RPC input, RPC output, action input, action output, or anydata node, is serialized using a CBOR map in which each schema node defined within is encoded using a key and a value.
This specification supports two types of CBOR keys: YANG Schema Item iDentifier (YANG SID), as defined in <a href="#sid" class="xref">Section 3.2</a>, and names, as defined in <a href="#name" class="xref">Section 3.3</a>. Each of these key types is encoded using a specific CBOR type that allows their interpretation during the deserialization process. Protocols or mechanisms implementing this specification can mandate the use of a specific key type or allow the generator to choose freely per key.<a href="#section-3-3" class="pilcrow">¶</a></p>
<p id="section-3-4">In order to minimize the size of the encoded data, the
mapping avoids any unnecessary meta-information beyond that directly
provided by the CBOR basic generic data model (<span><a href="https://www.rfc-editor.org/rfc/rfc8949#section-2" class="relref">Section 2</a> of [<a href="#RFC8949" class="xref">RFC8949</a>]</span>). For instance, CBOR tags are used solely in the case of an absolute SID, anyxml data nodes, or the union datatype to explicitly distinguish the use of different YANG datatypes encoded using the same CBOR major type.<a href="#section-3-4" class="pilcrow">¶</a></p>
<p id="section-3-5">Unless specified otherwise by the protocol or mechanism implementing this specification, the indefinite length encoding, as defined in <span><a href="https://www.rfc-editor.org/rfc/rfc8949#section-3.2" class="relref">Section 3.2</a> of [<a href="#RFC8949" class="xref">RFC8949</a>]</span>, <span class="bcp14">SHALL</span> be supported by the CBOR decoders employed with YANG-CBOR.
(This enables an implementation to begin emitting an array or map
before the number of entries in that structure is known, possibly also
avoiding excessive locking or race conditions.
On the other hand, it deprives the receiver of the encoded data from
advance announcement about some size information, so a generator
should choose indefinite length encoding only when these benefits do
accrue.)<a href="#section-3-5" class="pilcrow">¶</a></p>
<p id="section-3-6">Data nodes implemented using a CBOR array, map, byte string, or text string can be instantiated but empty. In this case, they are encoded with a length of zero.<a href="#section-3-6" class="pilcrow">¶</a></p>
<p id="section-3-7">When representation nodes are serialized using the rules defined by this specification as part of an application payload, the payload <span class="bcp14">SHOULD</span> include information that would allow each node to be identified in a stateless way, for instance, the SID number associated with the node, the SID delta from another SID in the application payload, the namespace-qualified name, or the instance-identifier.<a href="#section-3-7" class="pilcrow">¶</a></p>
<p id="section-3-8">Examples in <a href="#instance-encoding" class="xref">Section 4</a> include a root CBOR map with a single entry having a key set to either a namespace-qualified name or a SID. This root CBOR map is provided only as a typical usage example and is not part of the present encoding rules. Only the value within this CBOR map is compulsory.<a href="#section-3-8" class="pilcrow">¶</a></p>
<div id="cbor-diagnostic-notation">
<section id="section-3.1">
        <h3 id="name-cbor-diagnostic-notation">
<a href="#section-3.1" class="section-number selfRef">3.1. </a><a href="#name-cbor-diagnostic-notation" class="section-name selfRef">CBOR Diagnostic Notation</a>
        </h3>
<p id="section-3.1-1">Within this document, CBOR binary contents are represented using an equivalent textual form called CBOR diagnostic notation, as defined in <span><a href="https://www.rfc-editor.org/rfc/rfc8949#section-8" class="relref">Section 8</a> of [<a href="#RFC8949" class="xref">RFC8949</a>]</span>. This notation is used strictly for documentation purposes and is never used in the data serialization. <a href="#diagnostic-notation-summary" class="xref">Table 1</a> below provides a summary of this notation.<a href="#section-3.1-1" class="pilcrow">¶</a></p>
<span id="name-cbor-diagnostic-notation-su"></span><div id="diagnostic-notation-summary">
<table class="center" id="table-1">
          <caption>
<a href="#table-1" class="selfRef">Table 1</a>:
<a href="#name-cbor-diagnostic-notation-su" class="selfRef">CBOR Diagnostic Notation Summary</a>
          </caption>
<thead>
            <tr>
              <th class="text-left" rowspan="1" colspan="1">CBOR Content</th>
              <th class="text-left" rowspan="1" colspan="1">CBOR Type</th>
              <th class="text-left" rowspan="1" colspan="1">Diagnostic Notation</th>
              <th class="text-left" rowspan="1" colspan="1">Example</th>
              <th class="text-left" rowspan="1" colspan="1">CBOR Encoding</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">Unsigned integer</td>
              <td class="text-left" rowspan="1" colspan="1">0</td>
              <td class="text-left" rowspan="1" colspan="1">Decimal digits</td>
              <td class="text-left" rowspan="1" colspan="1">123</td>
              <td class="text-left" rowspan="1" colspan="1">18 7B</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">Negative integer</td>
              <td class="text-left" rowspan="1" colspan="1">1</td>
              <td class="text-left" rowspan="1" colspan="1">Decimal digits prefixed by a minus sign</td>
              <td class="text-left" rowspan="1" colspan="1">-123</td>
              <td class="text-left" rowspan="1" colspan="1">38 7A</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">Byte string</td>
              <td class="text-left" rowspan="1" colspan="1">2</td>
              <td class="text-left" rowspan="1" colspan="1">Hexadecimal value enclosed between single quotes and prefixed by an 'h'</td>
              <td class="text-left" rowspan="1" colspan="1">h'F15C'</td>
              <td class="text-left" rowspan="1" colspan="1">42 F15C</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">Text string</td>
              <td class="text-left" rowspan="1" colspan="1">3</td>
              <td class="text-left" rowspan="1" colspan="1">String of Unicode characters enclosed between double quotes</td>
              <td class="text-left" rowspan="1" colspan="1">"txt"</td>
              <td class="text-left" rowspan="1" colspan="1">63 747874</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">Array</td>
              <td class="text-left" rowspan="1" colspan="1">4</td>
              <td class="text-left" rowspan="1" colspan="1">Comma-separated list of values within square brackets</td>
              <td class="text-left" rowspan="1" colspan="1">[ 1, 2 ]</td>
              <td class="text-left" rowspan="1" colspan="1">82 01 02</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">Map</td>
              <td class="text-left" rowspan="1" colspan="1">5</td>
              <td class="text-left" rowspan="1" colspan="1">Comma-separated list of key : value pairs within curly braces</td>
              <td class="text-left" rowspan="1" colspan="1">{ 1: 123, 2: 456 }</td>
              <td class="text-left" rowspan="1" colspan="1">A2 01187B 021901C8</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">Boolean</td>
              <td class="text-left" rowspan="1" colspan="1">7/20</td>
              <td class="text-left" rowspan="1" colspan="1">false</td>
              <td class="text-left" rowspan="1" colspan="1">false</td>
              <td class="text-left" rowspan="1" colspan="1">F4</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1"> </td>
              <td class="text-left" rowspan="1" colspan="1">7/21</td>
              <td class="text-left" rowspan="1" colspan="1">true</td>
              <td class="text-left" rowspan="1" colspan="1">true</td>
              <td class="text-left" rowspan="1" colspan="1">F5</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">Null</td>
              <td class="text-left" rowspan="1" colspan="1">7/22</td>
              <td class="text-left" rowspan="1" colspan="1">null</td>
              <td class="text-left" rowspan="1" colspan="1">null</td>
              <td class="text-left" rowspan="1" colspan="1">F6</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">Not assigned</td>
              <td class="text-left" rowspan="1" colspan="1">7/23</td>
              <td class="text-left" rowspan="1" colspan="1">undefined</td>
              <td class="text-left" rowspan="1" colspan="1">undefined</td>
              <td class="text-left" rowspan="1" colspan="1">F7</td>
            </tr>
          </tbody>
        </table>
</div>
<p id="section-3.1-3">Note: CBOR binary contents shown in this specification are annotated with comments. These comments are delimited by slashes ("/"), as defined in <span><a href="https://www.rfc-editor.org/rfc/rfc8610#appendix-G.6" class="relref">Appendix G.6</a> of [<a href="#RFC8610" class="xref">RFC8610</a>]</span>.<a href="#section-3.1-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="sid">
<section id="section-3.2">
        <h3 id="name-yang-schema-item-identifier">
<a href="#section-3.2" class="section-number selfRef">3.2. </a><a href="#name-yang-schema-item-identifier" class="section-name selfRef">YANG Schema Item iDentifier</a>
        </h3>
<p id="section-3.2-1">Some of the items defined in YANG <span>[<a href="#RFC7950" class="xref">RFC7950</a>]</span> require the use of a unique identifier.  In both the Network Configuration Protocol (NETCONF) <span>[<a href="#RFC6241" class="xref">RFC6241</a>]</span> and RESTCONF <span>[<a href="#RFC8040" class="xref">RFC8040</a>]</span>, these identifiers are implemented using text strings.  To allow the implementation of data models defined in YANG in constrained devices and constrained networks, a more compact method to identify YANG items is required. This compact identifier, called "YANG Schema Item iDentifier", is an unsigned integer limited to 63 bits of range (i.e., 0..9223372036854775807 or 0..0x7fffffffffffffff). The following items are identified using YANG SIDs (often shortened to SIDs):<a href="#section-3.2-1" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-3.2-2.1">identities<a href="#section-3.2-2.1" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-3.2-2.2">data nodes<a href="#section-3.2-2.2" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-3.2-2.3">RPCs and associated input(s) and output(s)<a href="#section-3.2-2.3" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-3.2-2.4">actions and associated input(s) and output(s)<a href="#section-3.2-2.4" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-3.2-2.5">YANG data structures<a href="#section-3.2-2.5" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-3.2-2.6">notifications and associated information<a href="#section-3.2-2.6" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-3.2-2.7">YANG modules and features<a href="#section-3.2-2.7" class="pilcrow">¶</a>
</li>
        </ul>
<aside id="section-3.2-3">
          <p id="section-3.2-3.1">Note that any structuring of modules into submodules is transparent to YANG-CBOR:
SIDs are not allocated for the names of submodules, and any
items within a submodule are effectively allocated SIDs as part of
processing the module that includes them.<a href="#section-3.2-3.1" class="pilcrow">¶</a></p>
</aside>
<p id="section-3.2-4">To minimize their size, SIDs used as keys in CBOR maps are encoded
using deltas, i.e., signed (negative or unsigned) integers that are
added to the reference SID applying to the map.
The reference SID of an outermost map is zero, unless a different
reference SID is unambiguously conferred from the environment in which
the outermost map is used.
The reference SID of a map that is most directly embedded in a map entry
with a name-based key is zero.
For all other maps, the reference SID is the SID computed for the map
entry it is most directly embedded in.
(The embedding may be indirect if an array intervenes, e.g., in a YANG list.)
Where absolute SIDs are desired in map key positions (where a bare
integer implies a delta), they need to be identified as absolute SID values by using CBOR tag number 47 (as defined in <a href="#container-with-sid" class="xref">Section 4.2.1</a>).<a href="#section-3.2-4" class="pilcrow">¶</a></p>
<p id="section-3.2-5">Thus, conversion from SIDs to deltas and back to SIDs is a stateless
process solely based on the data serialized or deserialized combined
with, potentially, an outermost reference SID unambiguously conferred
by the environment.<a href="#section-3.2-5" class="pilcrow">¶</a></p>
<p id="section-3.2-6">Mechanisms and processes used to assign SIDs to YANG items and to guarantee their uniqueness are outside the scope of the present specification.
If SIDs are to be used, the present specification is used in conjunction with a specification defining this management.
A related document, i.e., <span>[<a href="#I-D.ietf-core-sid" class="xref">CORE-SID</a>]</span>, is intended to serve as the definitive way to assign SID values for YANG modules managed by the IETF and recommends itself for YANG modules managed by non-IETF entities, as well.
The present specification has been designed to allow different methods of assignment to be used within separate domains.<a href="#section-3.2-6" class="pilcrow">¶</a></p>
<p id="section-3.2-7">To provide implementations with a way to internally indicate the
absence of a SID, the SID value 0 is reserved and will not be
allocated; it is not used in interchange.<a href="#section-3.2-7" class="pilcrow">¶</a></p>
</section>
</div>
<div id="name">
<section id="section-3.3">
        <h3 id="name-name">
<a href="#section-3.3" class="section-number selfRef">3.3. </a><a href="#name-name" class="section-name selfRef">Name</a>
        </h3>
<p id="section-3.3-1">This specification also supports the encoding of YANG item identifiers as text strings, similar to those used by the JSON encoding of data modeled with YANG <span>[<a href="#RFC7951" class="xref">RFC7951</a>]</span>. This approach can be used to avoid the management overhead associated with SID allocation. The main drawback is the significant increase in size of the encoded data.<a href="#section-3.3-1" class="pilcrow">¶</a></p>
<p id="section-3.3-2">YANG item identifiers implemented using names <span class="bcp14">MUST</span> be in one of the following forms:<a href="#section-3.3-2" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-3.3-3.1">simple -- the identifier of the YANG item (i.e., schema node or identity).<a href="#section-3.3-3.1" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-3.3-3.2">namespace-qualified -- the identifier of the YANG item is prefixed with the name of the module in which this item is defined, separated by the colon character (":").<a href="#section-3.3-3.2" class="pilcrow">¶</a>
</li>
        </ul>
<p id="section-3.3-4">The name of a module determines the namespace of all YANG items defined in that module. If an item is defined in a submodule, then the namespace-qualified name uses the name of the main module to which the submodule belongs.<a href="#section-3.3-4" class="pilcrow">¶</a></p>
<p id="section-3.3-5">ABNF syntax <span>[<a href="#RFC5234" class="xref">RFC5234</a>]</span> of a name is shown in <a href="#namesyntax" class="xref">Figure 1</a>, where the production for "identifier" is defined in <span><a href="https://www.rfc-editor.org/rfc/rfc7950#section-14" class="relref">Section 14</a> of [<a href="#RFC7950" class="xref">RFC7950</a>]</span>.<a href="#section-3.3-5" class="pilcrow">¶</a></p>
<span id="name-abnf-production-for-a-simpl"></span><div id="namesyntax">
<figure id="figure-1">
          <div id="section-3.3-6.1">
<pre class="lang-abnf sourcecode">
name = [identifier ":"] identifier
</pre>
</div>
<figcaption><a href="#figure-1" class="selfRef">Figure 1</a>:
<a href="#name-abnf-production-for-a-simpl" class="selfRef">ABNF Production for a Simple or Namespace-Qualified Name</a>
          </figcaption></figure>
</div>
<p id="section-3.3-7">A namespace-qualified name <span class="bcp14">MUST</span> be used for all members of a top-level CBOR map and then also whenever the namespaces of the representation node and its parent node are different. In all other cases, the simple form of the name <span class="bcp14">MUST</span> be used.<a href="#section-3.3-7" class="pilcrow">¶</a></p>
<p id="section-3.3-8">Definition example:<a href="#section-3.3-8" class="pilcrow">¶</a></p>
<div id="section-3.3-9">
<pre class="lang-yang sourcecode">
module example-foomod {
  container top {
    leaf foo {
      type uint8;
    }
  }
}

module example-barmod {
  import example-foomod {
    prefix "foomod";
  }
  augment "/foomod:top" {
    leaf bar {
      type boolean;
    }
  }
}
</pre><a href="#section-3.3-9" class="pilcrow">¶</a>
</div>
<p id="section-3.3-10">A valid CBOR encoding of the 'top' container is as follows.<a href="#section-3.3-10" class="pilcrow">¶</a></p>
<p id="section-3.3-11">CBOR diagnostic notation:<a href="#section-3.3-11" class="pilcrow">¶</a></p>
<div id="section-3.3-12">
<pre class="lang-cbor-diag sourcecode">
{
  "example-foomod:top": {
    "foo": 54,
    "example-barmod:bar": true
  }
}
</pre><a href="#section-3.3-12" class="pilcrow">¶</a>
</div>
<p id="section-3.3-13">Both the 'top' container and the 'bar' leaf defined in a different YANG module as its parent container are encoded as namespace-qualified names. The 'foo' leaf defined in the same YANG module as its parent container is encoded as a simple name.<a href="#section-3.3-13" class="pilcrow">¶</a></p>
</section>
</div>
</section>
</div>
<div id="instance-encoding">
<section id="section-4">
      <h2 id="name-encoding-of-representation-">
<a href="#section-4" class="section-number selfRef">4. </a><a href="#name-encoding-of-representation-" class="section-name selfRef">Encoding of Representation Nodes</a>
      </h2>
<p id="section-4-1">Representation nodes defined using the YANG modeling language are encoded using CBOR <span>[<a href="#RFC8949" class="xref">RFC8949</a>]</span>, based on the rules defined in this section. We assume that the reader is
already familiar with both YANG <span>[<a href="#RFC7950" class="xref">RFC7950</a>]</span> and CBOR <span>[<a href="#RFC8949" class="xref">RFC8949</a>]</span>.<a href="#section-4-1" class="pilcrow">¶</a></p>
<div id="the-leaf">
<section id="section-4.1">
        <h3 id="name-the-leaf">
<a href="#section-4.1" class="section-number selfRef">4.1. </a><a href="#name-the-leaf" class="section-name selfRef">The 'leaf'</a>
        </h3>
<p id="section-4.1-1">A 'leaf' <span class="bcp14">MUST</span> be encoded accordingly to its datatype using one of the encoding rules specified in <a href="#data-types-mapping" class="xref">Section 6</a>.<a href="#section-4.1-1" class="pilcrow">¶</a></p>
<p id="section-4.1-2">The following examples show the encoding of a 'hostname' leaf using a SID or a name.<a href="#section-4.1-2" class="pilcrow">¶</a></p>
<p id="section-4.1-3">Definition example adapted from <span>[<a href="#RFC6991" class="xref">RFC6991</a>]</span> and <span>[<a href="#RFC7317" class="xref">RFC7317</a>]</span>:<a href="#section-4.1-3" class="pilcrow">¶</a></p>
<div id="section-4.1-4">
<pre class="lang-yang sourcecode">
typedef domain-name {
  type string {
    pattern
      '((([a-zA-Z0-9_]([a-zA-Z0-9\-_]){0,61})?[a-zA-Z0-9]\.)*'
    + '([a-zA-Z0-9_]([a-zA-Z0-9\-_]){0,61})?[a-zA-Z0-9]\.?)'
    + '|\.';
    length "1..253";
  }
}

leaf hostname {
  type inet:domain-name;
}
</pre><a href="#section-4.1-4" class="pilcrow">¶</a>
</div>
<div id="using-sids-in-keys">
<section id="section-4.1.1">
          <h4 id="name-using-sids-in-keys">
<a href="#section-4.1.1" class="section-number selfRef">4.1.1. </a><a href="#name-using-sids-in-keys" class="section-name selfRef">Using SIDs in Keys</a>
          </h4>
<p id="section-4.1.1-1">As with all examples below, the delta in the outermost map assumes a reference YANG SID (current schema node) of 0.<a href="#section-4.1.1-1" class="pilcrow">¶</a></p>
<p id="section-4.1.1-2">CBOR diagnostic notation:<a href="#section-4.1.1-2" class="pilcrow">¶</a></p>
<div id="section-4.1.1-3">
<pre class="lang-cbor-diag sourcecode">
{
  1752 : "myhost.example.com"     / hostname (SID 1752) /
}
</pre><a href="#section-4.1.1-3" class="pilcrow">¶</a>
</div>
<p id="section-4.1.1-4" class="keepWithNext">CBOR encoding:<a href="#section-4.1.1-4" class="pilcrow">¶</a></p>
<div id="section-4.1.1-5">
<pre class="lang-cbor-pretty sourcecode">
A1                                         # map(1)
   19 06D8                                 # unsigned(1752)
   72                                      # text(18)
      6D79686F73742E6578616D706C652E636F6D # "myhost.example.com"
</pre><a href="#section-4.1.1-5" class="pilcrow">¶</a>
</div>
</section>
</div>
<div id="using-names-in-keys">
<section id="section-4.1.2">
          <h4 id="name-using-names-in-keys">
<a href="#section-4.1.2" class="section-number selfRef">4.1.2. </a><a href="#name-using-names-in-keys" class="section-name selfRef">Using Names in Keys</a>
          </h4>
<p id="section-4.1.2-1">CBOR diagnostic notation:<a href="#section-4.1.2-1" class="pilcrow">¶</a></p>
<div id="section-4.1.2-2">
<pre class="lang-cbor-diag sourcecode">
{
  "ietf-system:hostname" : "myhost.example.com"
}
</pre><a href="#section-4.1.2-2" class="pilcrow">¶</a>
</div>
<p id="section-4.1.2-3" class="keepWithNext">CBOR encoding:<a href="#section-4.1.2-3" class="pilcrow">¶</a></p>
<div id="section-4.1.2-4">
<pre class="lang-cbor-pretty sourcecode">
A1                                         # map(1)
   74                                      # text(20)
      696574662D73797374656D3A686F73746E616D65
   72                                      # text(18)
      6D79686F73742E6578616D706C652E636F6D
</pre><a href="#section-4.1.2-4" class="pilcrow">¶</a>
</div>
</section>
</div>
</section>
</div>
<div id="container">
<section id="section-4.2">
        <h3 id="name-the-container-and-other-nod">
<a href="#section-4.2" class="section-number selfRef">4.2. </a><a href="#name-the-container-and-other-nod" class="section-name selfRef">The 'container' and Other Nodes from the Data Tree</a>
        </h3>
<p id="section-4.2-1">Instances of containers, YANG data structures, notification contents, RPC inputs, RPC outputs, action inputs, and action outputs <span class="bcp14">MUST</span> be encoded using a CBOR map data item (major type 5).
 The same encoding is also used for the list entries in a list (<a href="#list" class="xref">Section 4.4</a>) and for anydata nodes (<a href="#the-anydata" class="xref">Section 4.5</a>).
 Collectively, we speak of these instances as "container-like instances".<a href="#section-4.2-1" class="pilcrow">¶</a></p>
<p id="section-4.2-2">A map consists of pairs of data items, with each pair consisting of a key and a value. Each key within the CBOR map is set to a schema node identifier, and each value is set to the value of this representation node according to the instance datatype.<a href="#section-4.2-2" class="pilcrow">¶</a></p>
<p id="section-4.2-3">This specification supports two types of CBOR map keys: SID, as defined in <a href="#sid" class="xref">Section 3.2</a>, and names, as defined in <a href="#name" class="xref">Section 3.3</a>.<a href="#section-4.2-3" class="pilcrow">¶</a></p>
<p id="section-4.2-4">The following examples show the encoding of a 'system-state' container representation instance using SIDs or names.<a href="#section-4.2-4" class="pilcrow">¶</a></p>
<p id="section-4.2-5">Definition example adapted from <span>[<a href="#RFC6991" class="xref">RFC6991</a>]</span> and <span>[<a href="#RFC7317" class="xref">RFC7317</a>]</span>:<a href="#section-4.2-5" class="pilcrow">¶</a></p>
<div id="section-4.2-6">
<pre class="lang-yang sourcecode">
typedef date-and-time {
  type string {
    pattern '\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(\.\d+)?'
          + '(Z|[\+\-]\d{2}:\d{2})';
  }
}

container system-state {

  container clock {
    leaf current-datetime {
      type date-and-time;
    }

    leaf boot-datetime {
      type date-and-time;
    }
  }
}
</pre><a href="#section-4.2-6" class="pilcrow">¶</a>
</div>
<div id="container-with-sid">
<section id="section-4.2.1">
          <h4 id="name-using-sids-in-keys-2">
<a href="#section-4.2.1" class="section-number selfRef">4.2.1. </a><a href="#name-using-sids-in-keys-2" class="section-name selfRef">Using SIDs in Keys</a>
          </h4>
<p id="section-4.2.1-1">In the context of containers and other nodes from the data tree, CBOR map keys within inner CBOR maps can be encoded using deltas (bare integers) or absolute SIDs (tagged with tag number 47).<a href="#section-4.2.1-1" class="pilcrow">¶</a></p>
<p id="section-4.2.1-2">Delta values are computed as follows:<a href="#section-4.2.1-2" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-4.2.1-3.1">In the case of a 'container', deltas are equal to the SID of the current representation node minus the SID of the parent 'container'.<a href="#section-4.2.1-3.1" class="pilcrow">¶</a>
</li>
            <li class="normal" id="section-4.2.1-3.2">In the case of a 'list', deltas are equal to the SID of the current representation node minus the SID of the parent 'list'.<a href="#section-4.2.1-3.2" class="pilcrow">¶</a>
</li>
            <li class="normal" id="section-4.2.1-3.3">In the case of an 'RPC input' or 'RPC output', deltas are equal to the SID of the current representation node minus the SID of the 'RPC'.<a href="#section-4.2.1-3.3" class="pilcrow">¶</a>
</li>
            <li class="normal" id="section-4.2.1-3.4">In the case of an 'action input' or 'action output', deltas are equal to the SID of the current representation node minus the SID of the 'action'.<a href="#section-4.2.1-3.4" class="pilcrow">¶</a>
</li>
            <li class="normal" id="section-4.2.1-3.5">In the case of a 'notification content', deltas are equal to the SID of the current representation node minus the SID of the 'notification'.<a href="#section-4.2.1-3.5" class="pilcrow">¶</a>
</li>
          </ul>
<p id="section-4.2.1-4">CBOR diagnostic notation:<a href="#section-4.2.1-4" class="pilcrow">¶</a></p>
<div id="section-4.2.1-5">
<pre class="lang-cbor-diag sourcecode">
{
  1720 : {                              / system-state (SID 1720) /
    1 : {                               / clock  (SID 1721) /
      2 : "2015-10-02T14:47:24Z-05:00", / current-datetime(SID 1723)/
      1 : "2015-09-15T09:12:58Z-05:00"  / boot-datetime (SID 1722) /
    }
  }
}
</pre><a href="#section-4.2.1-5" class="pilcrow">¶</a>
</div>
<p id="section-4.2.1-6">CBOR encoding:<a href="#section-4.2.1-6" class="pilcrow">¶</a></p>
<span id="name-system-state-clock-encoding"></span><div id="Fig-system-clock">
<figure id="figure-2">
            <div id="section-4.2.1-7.1">
<pre class="lang-cbor-pretty sourcecode">
A1                                      # map(1)
   19 06B8                              # unsigned(1720)
   A1                                   # map(1)
      01                                # unsigned(1)
      A2                                # map(2)
         02                             # unsigned(2)
         78 1A                          # text(26)
            323031352D31302D30325431343A34373A32345A2D30353A3030
         01                             # unsigned(1)
         78 1A                          # text(26)
            323031352D30392D31355430393A31323A35385A2D30353A3030
</pre>
</div>
<figcaption><a href="#figure-2" class="selfRef">Figure 2</a>:
<a href="#name-system-state-clock-encoding" class="selfRef">System State Clock Encoding</a>
            </figcaption></figure>
</div>
</section>
</div>
<div id="container-with-name">
<section id="section-4.2.2">
          <h4 id="name-using-names-in-keys-2">
<a href="#section-4.2.2" class="section-number selfRef">4.2.2. </a><a href="#name-using-names-in-keys-2" class="section-name selfRef">Using Names in Keys</a>
          </h4>
<p id="section-4.2.2-1">CBOR map keys implemented using names <span class="bcp14">MUST</span> be encoded using a CBOR
text string data item (major type 3). A namespace-qualified name <span class="bcp14">MUST</span>
be used each time the namespace of a representation node and its parent
differ. In all other cases, the simple form of the name <span class="bcp14">MUST</span> be
used. Names and namespaces are defined in <span><a href="https://www.rfc-editor.org/rfc/rfc7951#section-4" class="relref">Section 4</a> of [<a href="#RFC7951" class="xref">RFC7951</a>]</span>.<a href="#section-4.2.2-1" class="pilcrow">¶</a></p>
<p id="section-4.2.2-2">The following example shows the encoding of a 'system' container representation node instance using names.<a href="#section-4.2.2-2" class="pilcrow">¶</a></p>
<p id="section-4.2.2-3">CBOR diagnostic notation:<a href="#section-4.2.2-3" class="pilcrow">¶</a></p>
<div id="section-4.2.2-4">
<pre class="lang-cbor-diag sourcecode">
{
  "ietf-system:system-state" : {
    "clock" : {
      "current-datetime" : "2015-10-02T14:47:24Z-05:00",
      "boot-datetime" : "2015-09-15T09:12:58Z-05:00"
    }
  }
}
</pre><a href="#section-4.2.2-4" class="pilcrow">¶</a>
</div>
<p id="section-4.2.2-5" class="keepWithNext">CBOR encoding:<a href="#section-4.2.2-5" class="pilcrow">¶</a></p>
<div id="section-4.2.2-6">
<pre class="lang-cbor-pretty sourcecode">
A1                                      # map(1)
   78 18                                # text(24)
      696574662D73797374656D3A73797374656D2D7374617465
   A1                                   # map(1)
      65                                # text(5)
         636C6F636B                     # "clock"
      A2                                # map(2)
         70                             # text(16)
            63757272656E742D6461746574696D65
         78 1A                          # text(26)
            323031352D31302D30325431343A34373A32345A2D30353A3030
         6D                             # text(13)
            626F6F742D6461746574696D65
         78 1A                          # text(26)
            323031352D30392D31355430393A31323A35385A2D30353A3030
</pre><a href="#section-4.2.2-6" class="pilcrow">¶</a>
</div>
</section>
</div>
</section>
</div>
<div id="leaf-list">
<section id="section-4.3">
        <h3 id="name-the-leaf-list">
<a href="#section-4.3" class="section-number selfRef">4.3. </a><a href="#name-the-leaf-list" class="section-name selfRef">The 'leaf-list'</a>
        </h3>
<p id="section-4.3-1">A leaf-list <span class="bcp14">MUST</span> be encoded using a CBOR array data item (major type 4). Each entry of this array <span class="bcp14">MUST</span> be encoded accordingly to its datatype using one of the encoding rules specified in <a href="#data-types-mapping" class="xref">Section 6</a>.<a href="#section-4.3-1" class="pilcrow">¶</a></p>
<p id="section-4.3-2">The following example shows the encoding of the 'search' leaf-list representation node instance containing two entries: "ietf.org" and "ieee.org".<a href="#section-4.3-2" class="pilcrow">¶</a></p>
<p id="section-4.3-3">Definition example adapted from <span>[<a href="#RFC6991" class="xref">RFC6991</a>]</span> and <span>[<a href="#RFC7317" class="xref">RFC7317</a>]</span>:<a href="#section-4.3-3" class="pilcrow">¶</a></p>
<div id="section-4.3-4">
<pre class="lang-yang sourcecode">
typedef domain-name {
  type string {
    pattern
      '((([a-zA-Z0-9_]([a-zA-Z0-9\-_]){0,61})?[a-zA-Z0-9]\.)*'
    + '([a-zA-Z0-9_]([a-zA-Z0-9\-_]){0,61})?[a-zA-Z0-9]\.?)'
    + '|\.';
    length "1..253";
  }
}

leaf-list search {
  type domain-name;
  ordered-by user;
}
</pre><a href="#section-4.3-4" class="pilcrow">¶</a>
</div>
<div id="using-sids-in-keys-1">
<section id="section-4.3.1">
          <h4 id="name-using-sids-in-keys-3">
<a href="#section-4.3.1" class="section-number selfRef">4.3.1. </a><a href="#name-using-sids-in-keys-3" class="section-name selfRef">Using SIDs in Keys</a>
          </h4>
<p id="section-4.3.1-1" class="keepWithNext">CBOR diagnostic notation:<a href="#section-4.3.1-1" class="pilcrow">¶</a></p>
<div id="section-4.3.1-2">
<pre class="lang-cbor-diag sourcecode">
{
  1746 : [ "ietf.org", "ieee.org" ]     / search (SID 1746) /
}
</pre><a href="#section-4.3.1-2" class="pilcrow">¶</a>
</div>
<p id="section-4.3.1-3">CBOR encoding:<a href="#section-4.3.1-3" class="pilcrow">¶</a></p>
<div id="section-4.3.1-4">
<pre class="lang-cbor-pretty sourcecode">
A1                        # map(1)
   19 06D2                # unsigned(1746)
   82                     # array(2)
      68                  # text(8)
         696574662E6F7267 # "ietf.org"
      68                  # text(8)
         696565652E6F7267 # "ieee.org"
</pre><a href="#section-4.3.1-4" class="pilcrow">¶</a>
</div>
</section>
</div>
<div id="using-names-in-keys-1">
<section id="section-4.3.2">
          <h4 id="name-using-names-in-keys-3">
<a href="#section-4.3.2" class="section-number selfRef">4.3.2. </a><a href="#name-using-names-in-keys-3" class="section-name selfRef">Using Names in Keys</a>
          </h4>
<p id="section-4.3.2-1">CBOR diagnostic notation:<a href="#section-4.3.2-1" class="pilcrow">¶</a></p>
<div id="section-4.3.2-2">
<pre class="lang-cbor-diag sourcecode">
{
  "ietf-system:search" : [ "ietf.org", "ieee.org" ]
}
</pre><a href="#section-4.3.2-2" class="pilcrow">¶</a>
</div>
<p id="section-4.3.2-3">CBOR encoding:<a href="#section-4.3.2-3" class="pilcrow">¶</a></p>
<div id="section-4.3.2-4">
<pre class="lang-cbor-pretty sourcecode">
A1                                         # map(1)
   72                                      # text(18)
      696574662D73797374656D3A736561726368 # "ietf-system:search"
   82                                      # array(2)
      68                                   # text(8)
         696574662E6F7267                  # "ietf.org"
      68                                   # text(8)
         696565652E6F7267                  # "ieee.org"
</pre><a href="#section-4.3.2-4" class="pilcrow">¶</a>
</div>
</section>
</div>
</section>
</div>
<div id="list">
<section id="section-4.4">
        <h3 id="name-the-list-and-the-list-entri">
<a href="#section-4.4" class="section-number selfRef">4.4. </a><a href="#name-the-list-and-the-list-entri" class="section-name selfRef">The 'list' and the 'list' Entries</a>
        </h3>
<p id="section-4.4-1">A list or a subset of a list <span class="bcp14">MUST</span> be encoded using a CBOR array data item (major type 4). Each list entry within this CBOR array is encoded using a CBOR map data item (major type 5) based on the encoding rules of a container-like instance, as defined in <a href="#container" class="xref">Section 4.2</a>.<a href="#section-4.4-1" class="pilcrow">¶</a></p>
<p id="section-4.4-2">It is important to note that this encoding rule also applies to a 'list' representation node instance that has a single entry.<a href="#section-4.4-2" class="pilcrow">¶</a></p>
<p id="section-4.4-3">The following examples show the encoding of a 'server' list using SIDs or names.<a href="#section-4.4-3" class="pilcrow">¶</a></p>
<p id="section-4.4-4">Definition example adapted from <span>[<a href="#RFC7317" class="xref">RFC7317</a>]</span>:<a href="#section-4.4-4" class="pilcrow">¶</a></p>
<div id="section-4.4-5">
<pre class="lang-yang sourcecode">
list server {
  key name;

  leaf name {
    type string;
  }
  choice transport {
    case udp {
      container udp {
        leaf address {
          type host;
          mandatory true;
        }
        leaf port {
          type port-number;
        }
      }
    }
  }
  leaf association-type {
    type enumeration {
      enum server;
      enum peer;
      enum pool;
    }
    default server;
  }
  leaf iburst {
    type boolean;
    default false;
  }
  leaf prefer {
    type boolean;
    default false;
  }
}
</pre><a href="#section-4.4-5" class="pilcrow">¶</a>
</div>
<div id="list-with-sid">
<section id="section-4.4.1">
          <h4 id="name-using-sids-in-keys-4">
<a href="#section-4.4.1" class="section-number selfRef">4.4.1. </a><a href="#name-using-sids-in-keys-4" class="section-name selfRef">Using SIDs in Keys</a>
          </h4>
<p id="section-4.4.1-1">The encoding rules of each 'list' entry are defined in <a href="#container-with-sid" class="xref">Section 4.2.1</a>.<a href="#section-4.4.1-1" class="pilcrow">¶</a></p>
<p id="section-4.4.1-2" class="keepWithNext">CBOR diagnostic notation:<a href="#section-4.4.1-2" class="pilcrow">¶</a></p>
<div id="section-4.4.1-3">
<pre class="lang-cbor-diag sourcecode">
{
  1756 : [                      / server (SID 1756) /
    {
      3 : "NRC TIC server",     / name (SID 1759) /
      5 : {                     / udp (SID 1761) /
        1 : "tic.nrc.ca",       / address (SID 1762) /
        2 : 123                 / port (SID 1763) /
      },
      1 : 0,                    / association-type (SID 1757) /
      2 : false,                / iburst (SID 1758) /
      4 : true                  / prefer (SID 1760) /
    },
    {
      3 : "NRC TAC server",     / name (SID 1759) /
      5 : {                     / udp (SID 1761) /
        1 : "tac.nrc.ca"        / address (SID 1762) /
      }
    }
  ]
}
</pre><a href="#section-4.4.1-3" class="pilcrow">¶</a>
</div>
<p id="section-4.4.1-4">CBOR encoding:<a href="#section-4.4.1-4" class="pilcrow">¶</a></p>
<div id="section-4.4.1-5">
<pre class="lang-cbor-pretty sourcecode">
A1                                      # map(1)
   19 06DC                              # unsigned(1756)
   82                                   # array(2)
      A5                                # map(5)
         03                             # unsigned(3)
         6E                             # text(14)
            4E52432054494320736572766572 # "NRC TIC server"
         05                             # unsigned(5)
         A2                             # map(2)
            01                          # unsigned(1)
            6A                          # text(10)
               7469632E6E72632E6361     # "tic.nrc.ca"
            02                          # unsigned(2)
            18 7B                       # unsigned(123)
         01                             # unsigned(1)
         00                             # unsigned(0)
         02                             # unsigned(2)
         F4                             # primitive(20)
         04                             # unsigned(4)
         F5                             # primitive(21)
      A2                                # map(2)
         03                             # unsigned(3)
         6E                             # text(14)
            4E52432054414320736572766572 # "NRC TAC server"
         05                             # unsigned(5)
         A1                             # map(1)
            01                          # unsigned(1)
            6A                          # text(10)
               7461632E6E72632E6361     # "tac.nrc.ca"
</pre><a href="#section-4.4.1-5" class="pilcrow">¶</a>
</div>
</section>
</div>
<div id="using-names-in-keys-2">
<section id="section-4.4.2">
          <h4 id="name-using-names-in-keys-4">
<a href="#section-4.4.2" class="section-number selfRef">4.4.2. </a><a href="#name-using-names-in-keys-4" class="section-name selfRef">Using Names in Keys</a>
          </h4>
<p id="section-4.4.2-1">The encoding rules of each 'list' entry are defined in <a href="#container-with-name" class="xref">Section 4.2.2</a>.<a href="#section-4.4.2-1" class="pilcrow">¶</a></p>
<p id="section-4.4.2-2">CBOR diagnostic notation:<a href="#section-4.4.2-2" class="pilcrow">¶</a></p>
<div id="section-4.4.2-3">
<pre class="lang-cbor-diag sourcecode">
{
  "ietf-system:server" : [
    {
      "name" : "NRC TIC server",
      "udp" : {
        "address" : "tic.nrc.ca",
        "port" : 123
      },
      "association-type" : 0,
      "iburst" : false,
      "prefer" : true
    },
    {
      "name" : "NRC TAC server",
      "udp" : {
        "address" : "tac.nrc.ca"
      }
    }
  ]
}
</pre><a href="#section-4.4.2-3" class="pilcrow">¶</a>
</div>
<p id="section-4.4.2-4" class="keepWithNext">CBOR encoding:<a href="#section-4.4.2-4" class="pilcrow">¶</a></p>
<div id="section-4.4.2-5">
<pre class="lang-cbor-pretty sourcecode">
A1                                      # map(1)
   72                                   # text(18)
      696574662D73797374656D3A736572766572
   82                                   # array(2)
      A5                                # map(5)
         64                             # text(4)
            6E616D65                    # "name"
         6E                             # text(14)
            4E52432054494320736572766572
         63                             # text(3)
            756470                      # "udp"
         A2                             # map(2)
            67                          # text(7)
               61646472657373           # "address"
            6A                          # text(10)
               7469632E6E72632E6361     # "tic.nrc.ca"
            64                          # text(4)
               706F7274                 # "port"
            18 7B                       # unsigned(123)
         70                             # text(16)
            6173736F63696174696F6E2D74797065
         00                             # unsigned(0)
         66                             # text(6)
            696275727374                # "iburst"
         F4                             # primitive(20)
         66                             # text(6)
            707265666572                # "prefer"
         F5                             # primitive(21)
      A2                                # map(2)
         64                             # text(4)
            6E616D65                    # "name"
         6E                             # text(14)
            4E52432054414320736572766572
         63                             # text(3)
            756470                      # "udp"
         A1                             # map(1)
            67                          # text(7)
               61646472657373           # "address"
            6A                          # text(10)
               7461632E6E72632E6361     # "tac.nrc.ca"
</pre><a href="#section-4.4.2-5" class="pilcrow">¶</a>
</div>
</section>
</div>
</section>
</div>
<div id="the-anydata">
<section id="section-4.5">
        <h3 id="name-the-anydata">
<a href="#section-4.5" class="section-number selfRef">4.5. </a><a href="#name-the-anydata" class="section-name selfRef">The 'anydata'</a>
        </h3>
<p id="section-4.5-1">An anydata node serves as a container for an arbitrary set of representation nodes that otherwise appear as normal YANG-modeled data. An anydata representation node instance is encoded using the same rules as a container, i.e., using a CBOR map data item (major type 5) based on the encoding rules of a container-like instance, as defined in <a href="#container" class="xref">Section 4.2</a>.<a href="#section-4.5-1" class="pilcrow">¶</a></p>
<p id="section-4.5-2">The following example shows a possible use of an anydata node. In this example, an anydata node is used to define a representation node containing a notification event; this representation node can be part of a YANG list to create an event logger.<a href="#section-4.5-2" class="pilcrow">¶</a></p>
<p id="section-4.5-3">Definition example:<a href="#section-4.5-3" class="pilcrow">¶</a></p>
<div id="section-4.5-4">
<pre class="lang-yang sourcecode">
module event-log {
  ...
  anydata last-event;                // SID 60123
}
</pre><a href="#section-4.5-4" class="pilcrow">¶</a>
</div>
<p id="section-4.5-5">This example also assumes the assistance of the following notification.<a href="#section-4.5-5" class="pilcrow">¶</a></p>
<div id="section-4.5-6">
<pre class="lang-yang sourcecode">
module example-port {
  ...

  notification example-port-fault {  // SID 60200
    leaf port-name {                 // SID 60201
      type string;
    }
    leaf port-fault {                // SID 60202
      type string;
    }
  }
}
</pre><a href="#section-4.5-6" class="pilcrow">¶</a>
</div>
<div id="using-sids-in-keys-2">
<section id="section-4.5.1">
          <h4 id="name-using-sids-in-keys-5">
<a href="#section-4.5.1" class="section-number selfRef">4.5.1. </a><a href="#name-using-sids-in-keys-5" class="section-name selfRef">Using SIDs in Keys</a>
          </h4>
<p id="section-4.5.1-1">CBOR diagnostic notation:<a href="#section-4.5.1-1" class="pilcrow">¶</a></p>
<div id="section-4.5.1-2">
<pre class="lang-cbor-diag sourcecode">
{
  60123 : {                   / last-event (SID 60123) /
    77 : {                    / example-port-fault (SID 60200) /
      1 : "0/4/21",           / port-name (SID 60201) /
      2 : "Open pin 2"        / port-fault (SID 60202) /
    }
  }
}
</pre><a href="#section-4.5.1-2" class="pilcrow">¶</a>
</div>
<p id="section-4.5.1-3" class="keepWithNext">CBOR encoding:<a href="#section-4.5.1-3" class="pilcrow">¶</a></p>
<div id="section-4.5.1-4">
<pre class="lang-cbor-pretty sourcecode">
A1                               # map(1)
   19 EADB                       # unsigned(60123)
   A1                            # map(1)
      18 4D                      # unsigned(77)
      A2                         # map(2)
         01                      # unsigned(1)
         66                      # text(6)
            302F342F3231         # "0/4/21"
         02                      # unsigned(2)
         6A                      # text(10)
            4F70656E2070696E2032 # "Open pin 2"
</pre><a href="#section-4.5.1-4" class="pilcrow">¶</a>
</div>
<p id="section-4.5.1-5">In some implementations, it might be simpler to use the absolute SID encoding (tag number 47) for the anydata root element.
CBOR diagnostic notation:<a href="#section-4.5.1-5" class="pilcrow">¶</a></p>
<div id="section-4.5.1-6">
<pre class="lang-cbor-diag sourcecode">
{
  60123 : {                   / last-event (SID 60123) /
    47(60200) : {             / event-port-fault (SID 60200) /
      1 : "0/4/21",           / port-name (SID 60201) /
      2 : "Open pin 2"        / port-fault (SID 60202) /
    }
  }
}
</pre><a href="#section-4.5.1-6" class="pilcrow">¶</a>
</div>
</section>
</div>
<div id="using-names-in-keys-3">
<section id="section-4.5.2">
          <h4 id="name-using-names-in-keys-5">
<a href="#section-4.5.2" class="section-number selfRef">4.5.2. </a><a href="#name-using-names-in-keys-5" class="section-name selfRef">Using Names in Keys</a>
          </h4>
<p id="section-4.5.2-1">CBOR diagnostic notation:<a href="#section-4.5.2-1" class="pilcrow">¶</a></p>
<div id="section-4.5.2-2">
<pre class="lang-cbor-diag sourcecode">
{
  "event-log:last-event" : {
    "example-port:example-port-fault" : {
      "port-name" : "0/4/21",
      "port-fault" : "Open pin 2"
    }
  }
}
</pre><a href="#section-4.5.2-2" class="pilcrow">¶</a>
</div>
<p id="section-4.5.2-3" class="keepWithNext">CBOR encoding:<a href="#section-4.5.2-3" class="pilcrow">¶</a></p>
<div id="section-4.5.2-4">
<pre class="lang-cbor-pretty sourcecode">
A1                                      # map(1)
   74                                   # text(20)
      6576656E742D6C6F673A6C6173742D6576656E74
   A1                                   # map(1)
      78 1F                             # text(31)
         6578616D706C652D706F72743A
         6578616D706C652D706F72742D6661756C74
      A2                                # map(2)
         69                             # text(9)
            706F72742D6E616D65          # "port-name"
         66                             # text(6)
            302F342F3231                # "0/4/21"
         6A                             # text(10)
            706F72742D6661756C74        # "port-fault"
         6A                             # text(10)
            4F70656E2070696E2032        # "Open pin 2"
</pre><a href="#section-4.5.2-4" class="pilcrow">¶</a>
</div>
</section>
</div>
</section>
</div>
<div id="the-anyxml">
<section id="section-4.6">
        <h3 id="name-the-anyxml">
<a href="#section-4.6" class="section-number selfRef">4.6. </a><a href="#name-the-anyxml" class="section-name selfRef">The 'anyxml'</a>
        </h3>
<p id="section-4.6-1">An anyxml representation node is used to serialize an arbitrary CBOR content, i.e., its value can be any CBOR binary object.
(The "xml" in the name is a misnomer that only applied to YANG-XML <span>[<a href="#RFC7950" class="xref">RFC7950</a>]</span>.)
An anyxml value <span class="bcp14">MAY</span> contain CBOR data items tagged with one of the tags listed in <a href="#tag-registry" class="xref">Section 9.3</a>. The tags listed in <a href="#tag-registry" class="xref">Section 9.3</a> <span class="bcp14">SHALL</span> be supported.<a href="#section-4.6-1" class="pilcrow">¶</a></p>
<p id="section-4.6-2">The following example shows a valid CBOR-encoded anyxml representation node instance consisting of a CBOR array containing the CBOR simple values 'true', 'null', and 'true'.<a href="#section-4.6-2" class="pilcrow">¶</a></p>
<p id="section-4.6-3">Definition example adapted from <span>[<a href="#RFC7951" class="xref">RFC7951</a>]</span>:<a href="#section-4.6-3" class="pilcrow">¶</a></p>
<div id="section-4.6-4">
<pre class="lang-yang sourcecode">
module bar-module {
  ...
  anyxml bar;      // SID 60000
}
</pre><a href="#section-4.6-4" class="pilcrow">¶</a>
</div>
<div id="using-sids-in-keys-3">
<section id="section-4.6.1">
          <h4 id="name-using-sids-in-keys-6">
<a href="#section-4.6.1" class="section-number selfRef">4.6.1. </a><a href="#name-using-sids-in-keys-6" class="section-name selfRef">Using SIDs in Keys</a>
          </h4>
<p id="section-4.6.1-1">CBOR diagnostic notation:<a href="#section-4.6.1-1" class="pilcrow">¶</a></p>
<div id="section-4.6.1-2">
<pre class="lang-cbor-diag sourcecode">
{
  60000 : [true, null, true]   / bar (SID 60000) /
}
</pre><a href="#section-4.6.1-2" class="pilcrow">¶</a>
</div>
<p id="section-4.6.1-3" class="keepWithNext">CBOR encoding:<a href="#section-4.6.1-3" class="pilcrow">¶</a></p>
<div id="section-4.6.1-4">
<pre class="lang-cbor-pretty sourcecode">
A1         # map(1)
   19 EA60 # unsigned(60000)
   83      # array(3)
      F5   # primitive(21)
      F6   # primitive(22)
      F5   # primitive(21)
</pre><a href="#section-4.6.1-4" class="pilcrow">¶</a>
</div>
</section>
</div>
<div id="using-names-in-keys-4">
<section id="section-4.6.2">
          <h4 id="name-using-names-in-keys-6">
<a href="#section-4.6.2" class="section-number selfRef">4.6.2. </a><a href="#name-using-names-in-keys-6" class="section-name selfRef">Using Names in Keys</a>
          </h4>
<p id="section-4.6.2-1">CBOR diagnostic notation:<a href="#section-4.6.2-1" class="pilcrow">¶</a></p>
<div id="section-4.6.2-2">
<pre class="lang-cbor-diag sourcecode">
{
  "bar-module:bar" : [true, null, true]   / bar (SID 60000) /
}
</pre><a href="#section-4.6.2-2" class="pilcrow">¶</a>
</div>
<p id="section-4.6.2-3">CBOR encoding:<a href="#section-4.6.2-3" class="pilcrow">¶</a></p>
<div id="section-4.6.2-4">
<pre class="lang-cbor-pretty sourcecode">
A1                                 # map(1)
   6E                              # text(14)
      6261722D6D6F64756C653A626172 # "bar-module:bar"
   83                              # array(3)
      F5                           # primitive(21)
      F6                           # primitive(22)
      F5                           # primitive(21)
</pre><a href="#section-4.6.2-4" class="pilcrow">¶</a>
</div>
</section>
</div>
</section>
</div>
</section>
</div>
<div id="encoding-of-yang-data-extension">
<section id="section-5">
      <h2 id="name-encoding-of-the-yang-data-e">
<a href="#section-5" class="section-number selfRef">5. </a><a href="#name-encoding-of-the-yang-data-e" class="section-name selfRef">Encoding of the 'yang-data' Extension</a>
      </h2>
<p id="section-5-1">The yang-data extension <span>[<a href="#RFC8040" class="xref">RFC8040</a>]</span> is used to define data structures in YANG
that are not intended to be implemented as part of a datastore.<a href="#section-5-1" class="pilcrow">¶</a></p>
<p id="section-5-2">The yang-data extension will specify a container that <span class="bcp14">MUST</span> be encoded using the encoding rules of nodes of data trees, as defined in <a href="#container" class="xref">Section 4.2</a>.<a href="#section-5-2" class="pilcrow">¶</a></p>
<p id="section-5-3">Just like YANG containers, the yang-data extension can be encoded using either SIDs or names.<a href="#section-5-3" class="pilcrow">¶</a></p>
<p id="section-5-4">Definition example adapted from <span><a href="https://datatracker.ietf.org/doc/html/draft-ietf-core-comi-11#appendix-A" class="relref">Appendix A</a> of [<a href="#I-D.ietf-core-comi" class="xref">CORE-COMI</a>]</span>:<a href="#section-5-4" class="pilcrow">¶</a></p>
<div id="section-5-5">
<pre class="lang-yang sourcecode">
module ietf-coreconf {
  ...

  import ietf-restconf {
    prefix rc;
  }

  rc:yang-data yang-errors {
    container error {
      leaf error-tag {
        type identityref {
          base error-tag;
        }
      }
      leaf error-app-tag {
        type identityref {
          base error-app-tag;
        }
      }
      leaf error-data-node {
        type instance-identifier;
      }
      leaf error-message {
        type string;
      }
    }
  }
}
</pre><a href="#section-5-5" class="pilcrow">¶</a>
</div>
<div id="using-sids-in-keys-4">
<section id="section-5.1">
        <h3 id="name-using-sids-in-keys-7">
<a href="#section-5.1" class="section-number selfRef">5.1. </a><a href="#name-using-sids-in-keys-7" class="section-name selfRef">Using SIDs in Keys</a>
        </h3>
<p id="section-5.1-1">The yang-data extensions encoded using SIDs are carried in a CBOR map containing a single item pair. The key of this item is set to the SID assigned to the yang-data extension container; the value is set to the CBOR encoding of this container, as defined in <a href="#container" class="xref">Section 4.2</a>.<a href="#section-5.1-1" class="pilcrow">¶</a></p>
<p id="section-5.1-2">This example shows a serialization example of the yang-errors yang-data extension, as defined in <span>[<a href="#I-D.ietf-core-comi" class="xref">CORE-COMI</a>]</span>, using SIDs, as defined in <a href="#sid" class="xref">Section 3.2</a>.<a href="#section-5.1-2" class="pilcrow">¶</a></p>
<p id="section-5.1-3">CBOR diagnostic notation:<a href="#section-5.1-3" class="pilcrow">¶</a></p>
<div id="section-5.1-4">
<pre class="lang-cbor-diag sourcecode">
{
  1024 : {                      / error  (SID 1024) /
    4 : 1011,                   / error-tag (SID 1028) /
                                / = invalid-value (SID 1011) /
    1 : 1018,                   / error-app-tag (SID 1025) /
                                / = not-in-range (SID 1018) /
    2 : 1740,                   / error-data-node (SID 1026) /
                                / = timezone-utc-offset (SID 1740) /
    3 : "Maximum exceeded"      / error-message (SID 1027) /
  }
}
</pre><a href="#section-5.1-4" class="pilcrow">¶</a>
</div>
<p id="section-5.1-5">CBOR encoding:<a href="#section-5.1-5" class="pilcrow">¶</a></p>
<div id="section-5.1-6">
<pre class="lang-cbor-pretty sourcecode">
A1                                      # map(1)
   19 0400                              # unsigned(1024)
   A4                                   # map(4)
      04                                # unsigned(4)
      19 03F3                           # unsigned(1011)
      01                                # unsigned(1)
      19 03FA                           # unsigned(1018)
      02                                # unsigned(2)
      19 06CC                           # unsigned(1740)
      03                                # unsigned(3)
      70                                # text(16)
         4D6178696D756D206578636565646564 # "Maximum exceeded"
</pre><a href="#section-5.1-6" class="pilcrow">¶</a>
</div>
</section>
</div>
<div id="using-names-in-keys-5">
<section id="section-5.2">
        <h3 id="name-using-names-in-keys-7">
<a href="#section-5.2" class="section-number selfRef">5.2. </a><a href="#name-using-names-in-keys-7" class="section-name selfRef">Using Names in Keys</a>
        </h3>
<p id="section-5.2-1">The yang-data extensions encoded using names are carried in a CBOR map containing a single item pair. The key of this item is set to the namespace-qualified name of the yang-data extension container; the value is set to the CBOR encoding of this container, as defined in <a href="#container" class="xref">Section 4.2</a>.<a href="#section-5.2-1" class="pilcrow">¶</a></p>
<p id="section-5.2-2">This example shows a serialization example of the yang-errors yang-data extension, as defined in <span>[<a href="#I-D.ietf-core-comi" class="xref">CORE-COMI</a>]</span>, using names, as defined <a href="#name" class="xref">Section 3.3</a>.<a href="#section-5.2-2" class="pilcrow">¶</a></p>
<p id="section-5.2-3">CBOR diagnostic notation:<a href="#section-5.2-3" class="pilcrow">¶</a></p>
<div id="section-5.2-4">
<pre class="lang-cbor-diag sourcecode">
{
  "ietf-coreconf:error" : {
    "error-tag" : "invalid-value",
    "error-app-tag" : "not-in-range",
    "error-data-node" : "timezone-utc-offset",
    "error-message" : "Maximum exceeded"
  }
}
</pre><a href="#section-5.2-4" class="pilcrow">¶</a>
</div>
<p id="section-5.2-5" class="keepWithNext">CBOR encoding:<a href="#section-5.2-5" class="pilcrow">¶</a></p>
<div id="section-5.2-6">
<pre class="lang-cbor-pretty sourcecode">
A1                                           # map(1)
   73                                        # text(19)
      696574662D636F7265636F6E663A6572726F72 # "ietf-coreconf:error"
   A4                                        # map(4)
      69                                     # text(9)
         6572726F722D746167                  # "error-tag"
      6D                                     # text(13)
         696E76616C69642D76616C7565          # "invalid-value"
      6D                                     # text(13)
         6572726F722D6170702D746167          # "error-app-tag"
      6C                                     # text(12)
         6E6F742D696E2D72616E6765            # "not-in-range"
      6F                                     # text(15)
         6572726F722D646174612D6E6F6465      # "error-data-node"
      73                                     # text(19)
         74696D657A6F6E652D7574632D6F6666736574
                                             # "timezone-utc-offset"
      6D                                     # text(13)
         6572726F722D6D657373616765          # "error-message"
      70                                     # text(16)
         4D6178696D756D206578636565646564    # "Maximum exceeded"
</pre><a href="#section-5.2-6" class="pilcrow">¶</a>
</div>
</section>
</div>
</section>
</div>
<div id="data-types-mapping">
<section id="section-6">
      <h2 id="name-representing-yang-data-type">
<a href="#section-6" class="section-number selfRef">6. </a><a href="#name-representing-yang-data-type" class="section-name selfRef">Representing YANG Data Types in CBOR</a>
      </h2>
<p id="section-6-1">The CBOR encoding of an instance of a leaf or leaf-list representation node
depends on the built-in type of that representation node. The following
subsection defines the CBOR encoding of each built-in type supported
by YANG, as listed in <span><a href="https://www.rfc-editor.org/rfc/rfc7950#section-4.2.4" class="relref">Section 4.2.4</a> of [<a href="#RFC7950" class="xref">RFC7950</a>]</span>. Each subsection shows an example value assigned to a representation node instance of the discussed built-in type.<a href="#section-6-1" class="pilcrow">¶</a></p>
<div id="the-unsigned-integer-types">
<section id="section-6.1">
        <h3 id="name-the-unsigned-integer-types">
<a href="#section-6.1" class="section-number selfRef">6.1. </a><a href="#name-the-unsigned-integer-types" class="section-name selfRef">The Unsigned Integer Types</a>
        </h3>
<p id="section-6.1-1">Leafs of type uint8, uint16, uint32, and uint64 <span class="bcp14">MUST</span> be encoded using a CBOR
unsigned integer data item (major type 0).<a href="#section-6.1-1" class="pilcrow">¶</a></p>
<p id="section-6.1-2">The following example shows the encoding of an 'mtu' leaf representation node instance set to 1280 bytes.<a href="#section-6.1-2" class="pilcrow">¶</a></p>
<p id="section-6.1-3">Definition example adapted from <span>[<a href="#RFC8344" class="xref">RFC8344</a>]</span>:<a href="#section-6.1-3" class="pilcrow">¶</a></p>
<div id="section-6.1-4">
<pre class="lang-yang sourcecode">
leaf mtu {
  type uint16 {
    range "68..max";
  }
}
</pre><a href="#section-6.1-4" class="pilcrow">¶</a>
</div>
<p id="section-6.1-5">CBOR diagnostic notation: 1280<a href="#section-6.1-5" class="pilcrow">¶</a></p>
<p id="section-6.1-6">CBOR encoding: 19 0500<a href="#section-6.1-6" class="pilcrow">¶</a></p>
</section>
</div>
<div id="the-integer-types">
<section id="section-6.2">
        <h3 id="name-the-integer-types">
<a href="#section-6.2" class="section-number selfRef">6.2. </a><a href="#name-the-integer-types" class="section-name selfRef">The Integer Types</a>
        </h3>
<p id="section-6.2-1">Leafs of type int8, int16, int32, and int64 <span class="bcp14">MUST</span> be encoded using either a CBOR
unsigned integer (major type 0) or a CBOR negative integer (major type 1), depending
on the actual value.<a href="#section-6.2-1" class="pilcrow">¶</a></p>
<p id="section-6.2-2">The following example shows the encoding of a 'timezone-utc-offset' leaf representation node instance set to -300 minutes.<a href="#section-6.2-2" class="pilcrow">¶</a></p>
<p id="section-6.2-3">Definition example adapted from <span>[<a href="#RFC7317" class="xref">RFC7317</a>]</span>:<a href="#section-6.2-3" class="pilcrow">¶</a></p>
<div id="section-6.2-4">
<pre class="lang-yang sourcecode">
leaf timezone-utc-offset {
  type int16 {
    range "-1500 .. 1500";
  }
}
</pre><a href="#section-6.2-4" class="pilcrow">¶</a>
</div>
<p id="section-6.2-5">CBOR diagnostic notation: -300<a href="#section-6.2-5" class="pilcrow">¶</a></p>
<p id="section-6.2-6">CBOR encoding: 39 012B<a href="#section-6.2-6" class="pilcrow">¶</a></p>
</section>
</div>
<div id="the-decimal64-type">
<section id="section-6.3">
        <h3 id="name-the-decimal64-type">
<a href="#section-6.3" class="section-number selfRef">6.3. </a><a href="#name-the-decimal64-type" class="section-name selfRef">The 'decimal64' Type</a>
        </h3>
<p id="section-6.3-1">Leafs of type decimal64 <span class="bcp14">MUST</span> be encoded using a decimal fraction, as defined in <span><a href="https://www.rfc-editor.org/rfc/rfc8949#section-3.4.4" class="relref">Section 3.4.4</a> of [<a href="#RFC8949" class="xref">RFC8949</a>]</span>.<a href="#section-6.3-1" class="pilcrow">¶</a></p>
<p id="section-6.3-2">The following example shows the encoding of a 'my-decimal' leaf representation node instance set to 2.57.<a href="#section-6.3-2" class="pilcrow">¶</a></p>
<p id="section-6.3-3">Definition example adapted from <span>[<a href="#RFC7317" class="xref">RFC7317</a>]</span>:<a href="#section-6.3-3" class="pilcrow">¶</a></p>
<div id="section-6.3-4">
<pre class="lang-yang sourcecode">
leaf my-decimal {
  type decimal64 {
    fraction-digits 2;
    range "1 .. 3.14 | 10 | 20..max";
  }
}
</pre><a href="#section-6.3-4" class="pilcrow">¶</a>
</div>
<p id="section-6.3-5">CBOR diagnostic notation: 4([-2, 257])<a href="#section-6.3-5" class="pilcrow">¶</a></p>
<p id="section-6.3-6">CBOR encoding: C4 82 21 19 0101<a href="#section-6.3-6" class="pilcrow">¶</a></p>
</section>
</div>
<div id="the-string-type">
<section id="section-6.4">
        <h3 id="name-the-string-type">
<a href="#section-6.4" class="section-number selfRef">6.4. </a><a href="#name-the-string-type" class="section-name selfRef">The 'string' Type</a>
        </h3>
<p id="section-6.4-1">Leafs of type string <span class="bcp14">MUST</span> be encoded using a CBOR text string data item (major
type 3).<a href="#section-6.4-1" class="pilcrow">¶</a></p>
<p id="section-6.4-2">The following example shows the encoding of a 'name' leaf representation node instance set to "eth0".<a href="#section-6.4-2" class="pilcrow">¶</a></p>
<p id="section-6.4-3">Definition example adapted from <span>[<a href="#RFC8343" class="xref">RFC8343</a>]</span>:<a href="#section-6.4-3" class="pilcrow">¶</a></p>
<div id="section-6.4-4">
<pre class="lang-yang sourcecode">
leaf name {
  type string;
}
</pre><a href="#section-6.4-4" class="pilcrow">¶</a>
</div>
<p id="section-6.4-5">CBOR diagnostic notation: "eth0"<a href="#section-6.4-5" class="pilcrow">¶</a></p>
<p id="section-6.4-6">CBOR encoding: 64 65746830<a href="#section-6.4-6" class="pilcrow">¶</a></p>
</section>
</div>
<div id="the-boolean-type">
<section id="section-6.5">
        <h3 id="name-the-boolean-type">
<a href="#section-6.5" class="section-number selfRef">6.5. </a><a href="#name-the-boolean-type" class="section-name selfRef">The 'boolean' Type</a>
        </h3>
<p id="section-6.5-1">Leafs of type boolean <span class="bcp14">MUST</span> be encoded using a CBOR simple value 'true' (major type 7, additional information 21) or 'false' (major type 7, additional information 20).<a href="#section-6.5-1" class="pilcrow">¶</a></p>
<p id="section-6.5-2">The following example shows the encoding of an 'enabled' leaf representation node instance set to 'true'.<a href="#section-6.5-2" class="pilcrow">¶</a></p>
<p id="section-6.5-3">Definition example adapted from <span>[<a href="#RFC7317" class="xref">RFC7317</a>]</span>:<a href="#section-6.5-3" class="pilcrow">¶</a></p>
<div id="section-6.5-4">
<pre class="lang-yang sourcecode">
leaf enabled {
  type boolean;
}
</pre><a href="#section-6.5-4" class="pilcrow">¶</a>
</div>
<p id="section-6.5-5">CBOR diagnostic notation: true<a href="#section-6.5-5" class="pilcrow">¶</a></p>
<p id="section-6.5-6">CBOR encoding: F5<a href="#section-6.5-6" class="pilcrow">¶</a></p>
</section>
</div>
<div id="enumeration">
<section id="section-6.6">
        <h3 id="name-the-enumeration-type">
<a href="#section-6.6" class="section-number selfRef">6.6. </a><a href="#name-the-enumeration-type" class="section-name selfRef">The 'enumeration' Type</a>
        </h3>
<p id="section-6.6-1">Leafs of type enumeration <span class="bcp14">MUST</span> be encoded using a CBOR unsigned
integer (major type 0) or CBOR negative integer (major type 1),
depending on the actual value, or exceptionally as a tagged text string (see below).
Enumeration values are either
explicitly assigned using the YANG statement 'value' or automatically
assigned based on the algorithm defined in <span><a href="https://www.rfc-editor.org/rfc/rfc7950#section-9.6.4.2" class="relref">Section 9.6.4.2</a> of [<a href="#RFC7950" class="xref">RFC7950</a>]</span>.<a href="#section-6.6-1" class="pilcrow">¶</a></p>
<p id="section-6.6-2">The following example shows the encoding of an 'oper-status' leaf representation node instance set to 'testing'.<a href="#section-6.6-2" class="pilcrow">¶</a></p>
<p id="section-6.6-3" class="keepWithNext">Definition example adapted from <span>[<a href="#RFC7317" class="xref">RFC7317</a>]</span>:<a href="#section-6.6-3" class="pilcrow">¶</a></p>
<div id="section-6.6-4">
<pre class="lang-yang sourcecode">
leaf oper-status {
  type enumeration {
    enum up { value 1; }
    enum down { value 2; }
    enum testing { value 3; }
    enum unknown { value 4; }
    enum dormant { value 5; }
    enum not-present { value 6; }
    enum lower-layer-down { value 7; }
  }
}
</pre><a href="#section-6.6-4" class="pilcrow">¶</a>
</div>
<p id="section-6.6-5">CBOR diagnostic notation: 3<a href="#section-6.6-5" class="pilcrow">¶</a></p>
<p id="section-6.6-6">CBOR encoding: 03<a href="#section-6.6-6" class="pilcrow">¶</a></p>
<p id="section-6.6-7">Values of 'enumeration' types defined in a 'union' type <span class="bcp14">MUST</span> be encoded using a
CBOR text string data item (major type 3) and <span class="bcp14">MUST</span> contain one of the names
assigned by 'enum' statements in YANG (see also <a href="#union" class="xref">Section 6.12</a>).
The encoding <span class="bcp14">MUST</span> be enclosed by the
enumeration CBOR tag, as specified in <a href="#tag-registry" class="xref">Section 9.3</a>.<a href="#section-6.6-7" class="pilcrow">¶</a></p>
<p id="section-6.6-8">Definition example adapted from <span>[<a href="#RFC7950" class="xref">RFC7950</a>]</span>:<a href="#section-6.6-8" class="pilcrow">¶</a></p>
<div id="section-6.6-9">
<pre class="lang-yang sourcecode">
type union {
  type int32;
  type enumeration {
    enum unbounded;
  }
}
</pre><a href="#section-6.6-9" class="pilcrow">¶</a>
</div>
<p id="section-6.6-10">CBOR diagnostic notation: 44("unbounded")<a href="#section-6.6-10" class="pilcrow">¶</a></p>
<p id="section-6.6-11">CBOR encoding: D8 2C 69 756E626F756E646564<a href="#section-6.6-11" class="pilcrow">¶</a></p>
</section>
</div>
<div id="bits">
<section id="section-6.7">
        <h3 id="name-the-bits-type">
<a href="#section-6.7" class="section-number selfRef">6.7. </a><a href="#name-the-bits-type" class="section-name selfRef">The 'bits' Type</a>
        </h3>
<p id="section-6.7-1">Keeping in mind that bit positions are either explicitly assigned using the
YANG statement 'position' or automatically assigned based on the algorithm
defined in <span><a href="https://www.rfc-editor.org/rfc/rfc7950#section-9.7.4.2" class="relref">Section 9.7.4.2</a> of [<a href="#RFC7950" class="xref">RFC7950</a>]</span>, each element of type bits could be seen
as a set of bit positions (or offsets from position 0) that have a value of
either 1, which represents the bit being set, or 0, which represents that the bit
is not set.<a href="#section-6.7-1" class="pilcrow">¶</a></p>
<p id="section-6.7-2">Leafs of type bits <span class="bcp14">MUST</span> be encoded either using a CBOR array (major type 4) or byte string
(major type 2) or exceptionally as a tagged text string (see below). In case CBOR array representation is used, each element is
either (1) a positive integer (major type 0 with value 0 being
disallowed) that can be used to calculate the offset of the next byte string or (2) a byte
string (major type 2) that carries the information regarding whether certain bits are set
or not. The initial offset value is 0, and each unsigned integer modifies the
offset value of the next byte string by the integer value multiplied by 8. For
example, if the bit offset is 0 and there is an integer with value 5, the first
byte of the byte string that follows will represent bit positions 40 to 47, with both
ends included. If the byte string has a second byte, it will carry information
about bits 48 to 55, and so on. Within each byte, bits are assigned from least
to most significant. After the byte string, the offset is modified by the number
of bytes in the byte string multiplied by 8.
Bytes with no bits set (zero bytes) at the end of the byte string are never generated.
If they occur at the end of the array, the zero bytes are simply omitted;
if they occur at the end of a byte string preceding an integer, the
zero bytes are removed and the integer is adjusted upwards by the number
of zero bytes that were removed.
An example follows.<a href="#section-6.7-2" class="pilcrow">¶</a></p>
<p id="section-6.7-3">The following example shows the encoding of an 'alarm-state' leaf representation node
instance with the 'critical' (position 2), 'warning' (position 8), and
'indeterminate' (position 128) flags set.<a href="#section-6.7-3" class="pilcrow">¶</a></p>
<div id="section-6.7-4">
<pre class="lang-yang sourcecode">
typedef alarm-state {
  type bits {
    bit unknown;
    bit under-repair;
    bit critical;
    bit major;
    bit minor;
    bit warning {
      position 8;
    }
    bit indeterminate {
      position 128;
    }
  }
}

leaf alarm-state {
  type alarm-state;
}
</pre><a href="#section-6.7-4" class="pilcrow">¶</a>
</div>
<p id="section-6.7-5">CBOR diagnostic notation: [h'0401', 14, h'01']<a href="#section-6.7-5" class="pilcrow">¶</a></p>
<p id="section-6.7-6">CBOR encoding: 83 42 0401 0E 41 01<a href="#section-6.7-6" class="pilcrow">¶</a></p>
<p id="section-6.7-7">In a number of cases, the array would only need to have one element -- a byte string with a few bytes inside.
For this case, it is <span class="bcp14">REQUIRED</span> to omit the array element and have only the byte array that would have been inside.
To illustrate this, let us consider the same example YANG definition but this time encoding only 'under-repair' and 'critical' flags.
The result would be<a href="#section-6.7-7" class="pilcrow">¶</a></p>
<p id="section-6.7-8">CBOR diagnostic notation: h'06'<a href="#section-6.7-8" class="pilcrow">¶</a></p>
<p id="section-6.7-9">CBOR encoding: 41 06<a href="#section-6.7-9" class="pilcrow">¶</a></p>
<p id="section-6.7-10">Elements in the array <span class="bcp14">MUST</span> be either byte strings that do not end in
a zero byte or positive unsigned
integers, where byte strings and integers <span class="bcp14">MUST</span> alternate, i.e., adjacent byte
strings or adjacent integers are an error. An array with a single byte string
<span class="bcp14">MUST</span> instead be encoded as just that byte string. An array with a single
positive integer is an error.
Note that a recipient can handle trailing zero bytes in the byte strings using the normal
rules without any issue, so an implementation <span class="bcp14">MAY</span> silently accept them.<a href="#section-6.7-10" class="pilcrow">¶</a></p>
<p id="section-6.7-11">Values of 'bits' types defined in a 'union' type <span class="bcp14">MUST</span> be encoded using a
CBOR text string data item (major type 3) and <span class="bcp14">MUST</span> contain a space-separated
sequence of names of 'bits' that are set (see also <a href="#union" class="xref">Section 6.12</a>).
The encoding <span class="bcp14">MUST</span> be enclosed by the
bits CBOR tag, as specified in <a href="#tag-registry" class="xref">Section 9.3</a>.<a href="#section-6.7-11" class="pilcrow">¶</a></p>
<p id="section-6.7-12">The following example shows the encoding of an 'alarm-state' leaf representation node
instance defined using a union type with the 'under-repair' and 'critical'
flags set.<a href="#section-6.7-12" class="pilcrow">¶</a></p>
<p id="section-6.7-13">Definition example:<a href="#section-6.7-13" class="pilcrow">¶</a></p>
<div id="section-6.7-14">
<pre class="lang-yang sourcecode">
leaf alarm-state-2 {
  type union {
    type alarm-state;
    type bits {
      bit extra-flag;
    }
  }
}
</pre><a href="#section-6.7-14" class="pilcrow">¶</a>
</div>
<p id="section-6.7-15">CBOR diagnostic notation: 43("under-repair critical")<a href="#section-6.7-15" class="pilcrow">¶</a></p>
<p id="section-6.7-16">CBOR encoding: D8 2B 75 756E6465722D72657061697220637269746963616C<a href="#section-6.7-16" class="pilcrow">¶</a></p>
</section>
</div>
<div id="the-binary-type">
<section id="section-6.8">
        <h3 id="name-the-binary-type">
<a href="#section-6.8" class="section-number selfRef">6.8. </a><a href="#name-the-binary-type" class="section-name selfRef">The 'binary' Type</a>
        </h3>
<p id="section-6.8-1">Leafs of type binary <span class="bcp14">MUST</span> be encoded using a CBOR byte string data item (major
type 2).<a href="#section-6.8-1" class="pilcrow">¶</a></p>
<p id="section-6.8-2">The following example shows the encoding of an 'aes128-key' leaf representation node
instance set to 0x1f1ce6a3f42660d888d92a4d8030476e.<a href="#section-6.8-2" class="pilcrow">¶</a></p>
<p id="section-6.8-3">Definition example:<a href="#section-6.8-3" class="pilcrow">¶</a></p>
<div id="section-6.8-4">
<pre class="lang-yang sourcecode">
leaf aes128-key {
  type binary {
    length 16;
  }
}
</pre><a href="#section-6.8-4" class="pilcrow">¶</a>
</div>
<p id="section-6.8-5">CBOR diagnostic notation: h'1F1CE6A3F42660D888D92A4D8030476E'<a href="#section-6.8-5" class="pilcrow">¶</a></p>
<p id="section-6.8-6">CBOR encoding: 50 1F1CE6A3F42660D888D92A4D8030476E<a href="#section-6.8-6" class="pilcrow">¶</a></p>
</section>
</div>
<div id="the-leafref-type">
<section id="section-6.9">
        <h3 id="name-the-leafref-type">
<a href="#section-6.9" class="section-number selfRef">6.9. </a><a href="#name-the-leafref-type" class="section-name selfRef">The 'leafref' Type</a>
        </h3>
<p id="section-6.9-1">Leafs of type leafref <span class="bcp14">MUST</span> be encoded using the rules of the representation node referenced
by the 'path' YANG statement.<a href="#section-6.9-1" class="pilcrow">¶</a></p>
<p id="section-6.9-2">The following example shows the encoding of an 'interface-state-ref' leaf representation node instance set to "eth1".<a href="#section-6.9-2" class="pilcrow">¶</a></p>
<p id="section-6.9-3">Definition example adapted from <span>[<a href="#RFC8343" class="xref">RFC8343</a>]</span>:<a href="#section-6.9-3" class="pilcrow">¶</a></p>
<div id="section-6.9-4">
<pre class="lang-yang sourcecode">
typedef interface-state-ref {
  type leafref {
    path "/interfaces-state/interface/name";
  }
}

container interfaces-state {
  list interface {
    key "name";
    leaf name {
      type string;
    }
    leaf-list higher-layer-if {
      type interface-state-ref;
    }
  }
}
</pre><a href="#section-6.9-4" class="pilcrow">¶</a>
</div>
<p id="section-6.9-5">CBOR diagnostic notation: "eth1"<a href="#section-6.9-5" class="pilcrow">¶</a></p>
<p id="section-6.9-6">CBOR encoding: 64 65746831<a href="#section-6.9-6" class="pilcrow">¶</a></p>
</section>
</div>
<div id="identityref">
<section id="section-6.10">
        <h3 id="name-the-identityref-type">
<a href="#section-6.10" class="section-number selfRef">6.10. </a><a href="#name-the-identityref-type" class="section-name selfRef">The 'identityref' Type</a>
        </h3>
<p id="section-6.10-1">This specification supports two approaches for encoding identityref:
as a YANG Schema Item iDentifier, as defined in <a href="#sid" class="xref">Section 3.2</a>, or as a name, 
as defined in <span><a href="https://www.rfc-editor.org/rfc/rfc7951#section-6.8" class="relref">Section 6.8</a> of [<a href="#RFC7951" class="xref">RFC7951</a>]</span>.
See <a href="#union" class="xref">Section 6.12</a> for an exceptional case when this representation needs to be tagged.<a href="#section-6.10-1" class="pilcrow">¶</a></p>
<div id="identityref-with-sid">
<section id="section-6.10.1">
          <h4 id="name-sids-as-identityref">
<a href="#section-6.10.1" class="section-number selfRef">6.10.1. </a><a href="#name-sids-as-identityref" class="section-name selfRef">SIDs as 'identityref'</a>
          </h4>
<p id="section-6.10.1-1">When representation nodes of type identityref are implemented using SIDs, they <span class="bcp14">MUST</span> be encoded using a CBOR unsigned integer data item (major type 0).
   (Note that, as they are not used in the position of CBOR map keys, no delta mechanism is employed for SIDs used for identityref.)<a href="#section-6.10.1-1" class="pilcrow">¶</a></p>
<p id="section-6.10.1-2">The following example shows the encoding of a 'type' leaf representation node instance set to the value 'iana-if-type:ethernetCsmacd' (SID 1880).<a href="#section-6.10.1-2" class="pilcrow">¶</a></p>
<p id="section-6.10.1-3">Definition example adapted from <span>[<a href="#RFC7317" class="xref">RFC7317</a>]</span>:<a href="#section-6.10.1-3" class="pilcrow">¶</a></p>
<div id="section-6.10.1-4">
<pre class="lang-yang sourcecode">
identity interface-type {
}

identity iana-interface-type {
  base interface-type;
}

identity ethernetCsmacd {
  base iana-interface-type;
}

leaf type {
  type identityref {
    base interface-type;
  }
}
</pre><a href="#section-6.10.1-4" class="pilcrow">¶</a>
</div>
<p id="section-6.10.1-5">CBOR diagnostic notation: 1880<a href="#section-6.10.1-5" class="pilcrow">¶</a></p>
<p id="section-6.10.1-6">CBOR encoding: 19 0758<a href="#section-6.10.1-6" class="pilcrow">¶</a></p>
</section>
</div>
<div id="name-as-identityref">
<section id="section-6.10.2">
          <h4 id="name-name-as-identityref">
<a href="#section-6.10.2" class="section-number selfRef">6.10.2. </a><a href="#name-name-as-identityref" class="section-name selfRef">Name as 'identityref'</a>
          </h4>
<p id="section-6.10.2-1">Alternatively, an identityref <span class="bcp14">MAY</span> be encoded using a name, as defined in <a href="#name" class="xref">Section 3.3</a>.  When names are used, identityref <span class="bcp14">MUST</span> be encoded using a CBOR text string data item (major type 3). If the identity is defined in a different module than the leaf node containing the identityref data node, the namespace-qualified form <span class="bcp14">MUST</span> be used. Otherwise, both the simple and namespace-qualified forms are permitted. Names and namespaces are defined in <a href="#name" class="xref">Section 3.3</a>.<a href="#section-6.10.2-1" class="pilcrow">¶</a></p>
<p id="section-6.10.2-2">The following example shows the encoding of the identity 'iana-if-type:ethernetCsmacd' using its namespace-qualified name. This example is described in <a href="#identityref-with-sid" class="xref">Section 6.10.1</a>.<a href="#section-6.10.2-2" class="pilcrow">¶</a></p>
<p id="section-6.10.2-3">CBOR diagnostic notation: "iana-if-type:ethernetCsmacd"<a href="#section-6.10.2-3" class="pilcrow">¶</a></p>
<p id="section-6.10.2-4">CBOR encoding: 78 1B 69616E612D69662D747970653A65746865726E657443736D616364<a href="#section-6.10.2-4" class="pilcrow">¶</a></p>
</section>
</div>
</section>
</div>
<div id="the-empty-type">
<section id="section-6.11">
        <h3 id="name-the-empty-type">
<a href="#section-6.11" class="section-number selfRef">6.11. </a><a href="#name-the-empty-type" class="section-name selfRef">The 'empty' Type</a>
        </h3>
<p id="section-6.11-1">Leafs of type empty <span class="bcp14">MUST</span> be encoded using the CBOR null value (major type
7, additional information 22).<a href="#section-6.11-1" class="pilcrow">¶</a></p>
<p id="section-6.11-2">The following example shows the encoding of an 'is-router' leaf representation node instance when present.<a href="#section-6.11-2" class="pilcrow">¶</a></p>
<p id="section-6.11-3">Definition example adapted from <span>[<a href="#RFC8344" class="xref">RFC8344</a>]</span>:<a href="#section-6.11-3" class="pilcrow">¶</a></p>
<div id="section-6.11-4">
<pre class="lang-yang sourcecode">
leaf is-router {
  type empty;
}
</pre><a href="#section-6.11-4" class="pilcrow">¶</a>
</div>
<p id="section-6.11-5">CBOR diagnostic notation: null<a href="#section-6.11-5" class="pilcrow">¶</a></p>
<p id="section-6.11-6">CBOR encoding: F6<a href="#section-6.11-6" class="pilcrow">¶</a></p>
</section>
</div>
<div id="union">
<section id="section-6.12">
        <h3 id="name-the-union-type">
<a href="#section-6.12" class="section-number selfRef">6.12. </a><a href="#name-the-union-type" class="section-name selfRef">The 'union' Type</a>
        </h3>
<p id="section-6.12-1">Leafs of type union <span class="bcp14">MUST</span> be encoded using the rules associated with one of the types listed.
When used in a union, the following YANG datatypes are enclosed by a CBOR tag to avoid confusion
between different YANG datatypes encoded using the same CBOR major type.<a href="#section-6.12-1" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-6.12-2.1">bits<a href="#section-6.12-2.1" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-6.12-2.2">enumeration<a href="#section-6.12-2.2" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-6.12-2.3">identityref<a href="#section-6.12-2.3" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-6.12-2.4">instance-identifier<a href="#section-6.12-2.4" class="pilcrow">¶</a>
</li>
        </ul>
<p id="section-6.12-3">See <a href="#tag-registry" class="xref">Section 9.3</a> for the assigned value of these CBOR tags.<a href="#section-6.12-3" class="pilcrow">¶</a></p>
<p id="section-6.12-4">As mentioned in Sections <a href="#enumeration" class="xref">6.6</a> and in <a href="#bits" class="xref">6.7</a>, 'enumeration' and 'bits' are encoded as a CBOR text string data item (major type 3) when defined within a 'union' type.
(This adds considerable complexity but is necessary because of an
idiosyncrasy of the YANG data model for unions; the work-around allows
compatibility to be maintained with the encoding of overlapping unions
in XML and JSON.
See also <span><a href="https://www.rfc-editor.org/rfc/rfc7950#section-9.12" class="relref">Section 9.12</a> of [<a href="#RFC7950" class="xref">RFC7950</a>]</span>.)<a href="#section-6.12-4" class="pilcrow">¶</a></p>
<p id="section-6.12-5">The following example shows the encoding of an 'ip-address' leaf representation node instance when set to "2001:db8:a0b:12f0::1".<a href="#section-6.12-5" class="pilcrow">¶</a></p>
<p id="section-6.12-6" class="keepWithNext">Definition example adapted from <span>[<a href="#RFC6991" class="xref">RFC6991</a>]</span>:<a href="#section-6.12-6" class="pilcrow">¶</a></p>
<div id="section-6.12-7">
<pre class="lang-yang sourcecode">
typedef ipv4-address {
  type string {
    pattern
      '(([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.){3}'
    +  '([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])'
    + '(%[\p{N}\p{L}]+)?';
  }
}

typedef ipv6-address {
  type string {
    pattern '((:|[0-9a-fA-F]{0,4}):)([0-9a-fA-F]{0,4}:){0,5}'
          + '((([0-9a-fA-F]{0,4}:)?(:|[0-9a-fA-F]{0,4}))|'
          + '(((25[0-5]|2[0-4][0-9]|[01]?[0-9]?[0-9])\.){3}'
          + '(25[0-5]|2[0-4][0-9]|[01]?[0-9]?[0-9])))'
          + '(%[\p{N}\p{L}]+)?';
    pattern '(([^:]+:){6}(([^:]+:[^:]+)|(.*\..*)))|'
          + '((([^:]+:)*[^:]+)?::(([^:]+:)*[^:]+)?)'
          + '(%.+)?';
  }
}

typedef ip-address {
  type union {
    type ipv4-address;
    type ipv6-address;
  }
}

leaf address {
  type ip-address;
}
</pre><a href="#section-6.12-7" class="pilcrow">¶</a>
</div>
<p id="section-6.12-8">CBOR diagnostic notation: "2001:db8:a0b:12f0::1"<a href="#section-6.12-8" class="pilcrow">¶</a></p>
<p id="section-6.12-9">CBOR encoding: 74 323030313A6462383A6130623A313266303A3A31<a href="#section-6.12-9" class="pilcrow">¶</a></p>
</section>
</div>
<div id="instance-id">
<section id="section-6.13">
        <h3 id="name-the-instance-identifier-typ">
<a href="#section-6.13" class="section-number selfRef">6.13. </a><a href="#name-the-instance-identifier-typ" class="section-name selfRef">The 'instance-identifier' Type</a>
        </h3>
<p id="section-6.13-1">This specification supports two approaches for encoding an instance-identifier: one based on YANG Schema Item iDentifier, as defined in <a href="#sid" class="xref">Section 3.2</a>, and one based on names, as defined in <a href="#name" class="xref">Section 3.3</a>.
See <a href="#union" class="xref">Section 6.12</a> for an exceptional case when this representation needs to be tagged.<a href="#section-6.13-1" class="pilcrow">¶</a></p>
<div id="instance-identifier-with-sid">
<section id="section-6.13.1">
          <h4 id="name-sids-as-instance-identifier">
<a href="#section-6.13.1" class="section-number selfRef">6.13.1. </a><a href="#name-sids-as-instance-identifier" class="section-name selfRef">SIDs as 'instance-identifier'</a>
          </h4>
<p id="section-6.13.1-1">SIDs uniquely identify a schema node. In the case of a single instance schema node, i.e., a schema node defined at the root of a YANG module or submodule or schema nodes defined within a container, the SID is sufficient to identify this instance (representation node).   
   (Note that no delta mechanism is employed for SIDs used for identityref, see <a href="#identityref-with-sid" class="xref">Section 6.10.1</a>.)<a href="#section-6.13.1-1" class="pilcrow">¶</a></p>
<p id="section-6.13.1-2">In the case of a representation node that is an entry of a YANG list, a SID is combined with the list key(s) to identify each instance within the YANG list(s).<a href="#section-6.13.1-2" class="pilcrow">¶</a></p>
<p id="section-6.13.1-3">Instance-identifiers of single instance schema nodes <span class="bcp14">MUST</span> be encoded using a CBOR unsigned integer data item (major type 0) and set to the targeted schema node SID.<a href="#section-6.13.1-3" class="pilcrow">¶</a></p>
<p id="section-6.13.1-4">Instance-identifiers of representation node entries of a YANG list <span class="bcp14">MUST</span> be encoded using a CBOR array data item (major type 4) containing the following entries:<a href="#section-6.13.1-4" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-6.13.1-5.1">The first entry <span class="bcp14">MUST</span> be encoded as a CBOR unsigned integer data item (major type 0) and set to the targeted schema node SID.<a href="#section-6.13.1-5.1" class="pilcrow">¶</a>
</li>
            <li class="normal" id="section-6.13.1-5.2">The following entries <span class="bcp14">MUST</span> contain the value of each key required to identify the instance of the targeted schema node. These keys <span class="bcp14">MUST</span> be ordered as defined in the 'key' YANG statement, starting from the top-level list, and followed by each subordinate list(s).<a href="#section-6.13.1-5.2" class="pilcrow">¶</a>
</li>
          </ul>
<p id="section-6.13.1-6">Examples within this section assume the definition of a schema node of type 'instance-identifier':<a href="#section-6.13.1-6" class="pilcrow">¶</a></p>
<p id="section-6.13.1-7">Definition example adapted from <span>[<a href="#RFC7950" class="xref">RFC7950</a>]</span>:<a href="#section-6.13.1-7" class="pilcrow">¶</a></p>
<div id="section-6.13.1-8">
<pre class="lang-yang sourcecode">
container system {
  ...
  leaf reporting-entity {
    type instance-identifier;
  }
</pre><a href="#section-6.13.1-8" class="pilcrow">¶</a>
</div>
<p id="section-6.13.1-9"><strong>First example:</strong><a href="#section-6.13.1-9" class="pilcrow">¶</a></p>
<p id="section-6.13.1-10">The following example shows the encoding of the 'reporting-entity' value referencing data node instance "/system/contact" (SID 1741).<a href="#section-6.13.1-10" class="pilcrow">¶</a></p>
<p id="section-6.13.1-11">Definition example adapted from <span>[<a href="#RFC7317" class="xref">RFC7317</a>]</span>:<a href="#section-6.13.1-11" class="pilcrow">¶</a></p>
<div id="section-6.13.1-12">
<pre class="lang-yang sourcecode">
container system {

  leaf contact {
    type string;
  }

  leaf hostname {
    type inet:domain-name;
  }
}
</pre><a href="#section-6.13.1-12" class="pilcrow">¶</a>
</div>
<p id="section-6.13.1-13">CBOR diagnostic notation: 1741<a href="#section-6.13.1-13" class="pilcrow">¶</a></p>
<p id="section-6.13.1-14">CBOR encoding: 19 06CD<a href="#section-6.13.1-14" class="pilcrow">¶</a></p>
<p id="section-6.13.1-15" class="keepWithNext"><strong>Second example:</strong><a href="#section-6.13.1-15" class="pilcrow">¶</a></p>
<p id="section-6.13.1-16">This example aims to show how a representation node entry of a YANG list is identified.
It uses a somewhat arbitrarily modified YANG module version from <span>[<a href="#RFC7317" class="xref">RFC7317</a>]</span> by
adding <code>country</code> to the leafs and keys of <code>authorized-key</code>.<a href="#section-6.13.1-16" class="pilcrow">¶</a></p>
<p id="section-6.13.1-17">The following example shows the encoding of the 'reporting-entity' value referencing list instance "/system/authentication/user/authorized-key/key-data" (which is assumed to have SID 1734) for username "bob" and authorized-key with name "admin" and country "france".<a href="#section-6.13.1-17" class="pilcrow">¶</a></p>
<div id="section-6.13.1-18">
<pre class="lang-yang sourcecode">
list user {
  key name;

  leaf name {
    type string;
  }

  leaf password {
    type ianach:crypt-hash;
  }

  list authorized-key {
    key "name country";

    leaf country {
      type string;
    }

    leaf name {
      type string;
    }

    leaf algorithm {
      type string;
    }

    leaf key-data {
      type binary;
    }
  }
}
</pre><a href="#section-6.13.1-18" class="pilcrow">¶</a>
</div>
<p id="section-6.13.1-19">CBOR diagnostic notation: [1734, "bob", "admin", "france"]<a href="#section-6.13.1-19" class="pilcrow">¶</a></p>
<p id="section-6.13.1-20" class="keepWithNext">CBOR encoding:<a href="#section-6.13.1-20" class="pilcrow">¶</a></p>
<div id="section-6.13.1-21">
<pre class="lang-cbor-pretty sourcecode">
84                 # array(4)
   19 06C6         # unsigned(1734)
   63              # text(3)
      626F62       # "bob"
   65              # text(5)
      61646D696E   # "admin"
   66              # text(6)
      6672616E6365 # "france"
</pre><a href="#section-6.13.1-21" class="pilcrow">¶</a>
</div>
<p id="section-6.13.1-22"><strong>Third example:</strong><a href="#section-6.13.1-22" class="pilcrow">¶</a></p>
<p id="section-6.13.1-23">The following example shows the encoding of the 'reporting-entity' value referencing the list instance "/system/authentication/user" (SID 1730), corresponding to username "jack".<a href="#section-6.13.1-23" class="pilcrow">¶</a></p>
<p id="section-6.13.1-24">CBOR diagnostic notation: [1730, "jack"]<a href="#section-6.13.1-24" class="pilcrow">¶</a></p>
<p id="section-6.13.1-25">CBOR encoding:<a href="#section-6.13.1-25" class="pilcrow">¶</a></p>
<div id="section-6.13.1-26">
<pre class="lang-cbor-pretty sourcecode">
82             # array(2)
   19 06C2     # unsigned(1730)
   64          # text(4)
      6A61636B # "jack"
</pre><a href="#section-6.13.1-26" class="pilcrow">¶</a>
</div>
</section>
</div>
<div id="names-as-instance-identifier">
<section id="section-6.13.2">
          <h4 id="name-names-as-instance-identifie">
<a href="#section-6.13.2" class="section-number selfRef">6.13.2. </a><a href="#name-names-as-instance-identifie" class="section-name selfRef">Names as 'instance-identifier'</a>
          </h4>
<p id="section-6.13.2-1">An 'instance-identifier' value is encoded as a text string that is
analogous to the lexical representation in XML encoding; see <span><a href="https://www.rfc-editor.org/rfc/rfc7950#section-9.13.2" class="relref">Section 9.13.2</a> of [<a href="#RFC7950" class="xref">RFC7950</a>]</span>. However, the encoding of namespaces in instance-identifier values follows the rules stated in <a href="#name" class="xref">Section 3.3</a>, namely:<a href="#section-6.13.2-1" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-6.13.2-2.1">The leftmost (top-level) data node name is always in the namespace-qualified form.<a href="#section-6.13.2-2.1" class="pilcrow">¶</a>
</li>
            <li class="normal" id="section-6.13.2-2.2">Any subsequent data node name is in the namespace-qualified form if the node is defined in a module other than its parent node; otherwise, the simple form is used. This rule also holds for node names appearing in predicates.<a href="#section-6.13.2-2.2" class="pilcrow">¶</a>
</li>
          </ul>
<p id="section-6.13.2-3">For example,<a href="#section-6.13.2-3" class="pilcrow">¶</a></p>
<p id="section-6.13.2-4">/ietf-interfaces:interfaces/interface[name='eth0']/ietf-ip:ipv4/ip<a href="#section-6.13.2-4" class="pilcrow">¶</a></p>
<p id="section-6.13.2-5">is a valid instance-identifier value because the data nodes "interfaces", "interface", and "name" are defined in the module "ietf-interfaces", whereas "ipv4" and "ip" are defined in "ietf-ip".<a href="#section-6.13.2-5" class="pilcrow">¶</a></p>
<p id="section-6.13.2-6">The resulting XML Path Language (XPath) <span class="bcp14">MUST</span> be encoded using a CBOR text string data item (major type 3).<a href="#section-6.13.2-6" class="pilcrow">¶</a></p>
<p id="section-6.13.2-7"><strong>First example:</strong><a href="#section-6.13.2-7" class="pilcrow">¶</a></p>
<p id="section-6.13.2-8">This example is described in <a href="#instance-identifier-with-sid" class="xref">Section 6.13.1</a>.<a href="#section-6.13.2-8" class="pilcrow">¶</a></p>
<p id="section-6.13.2-9">CBOR diagnostic notation: "/ietf-system:system/contact"<a href="#section-6.13.2-9" class="pilcrow">¶</a></p>
<p id="section-6.13.2-10">CBOR encoding:<a href="#section-6.13.2-10" class="pilcrow">¶</a></p>
<div id="section-6.13.2-11">
<pre class="lang-cbor-pretty sourcecode">
78 1B 2F696574662D73797374656D3A73797374656D2F636F6E74616374
</pre><a href="#section-6.13.2-11" class="pilcrow">¶</a>
</div>
<p id="section-6.13.2-12"><strong>Second example:</strong><a href="#section-6.13.2-12" class="pilcrow">¶</a></p>
<p id="section-6.13.2-13">This example is described in <a href="#instance-identifier-with-sid" class="xref">Section 6.13.1</a>.<a href="#section-6.13.2-13" class="pilcrow">¶</a></p>
<p id="section-6.13.2-14">CBOR diagnostic notation (the line break is inserted for exposition only):<a href="#section-6.13.2-14" class="pilcrow">¶</a></p>
<div id="section-6.13.2-15">
<pre class="lang-cbor-diag sourcecode">
"/ietf-system:system/authentication/user[name='bob']/
authorized-key[name='admin'][country='france']/key-data"
</pre><a href="#section-6.13.2-15" class="pilcrow">¶</a>
</div>
<p id="section-6.13.2-16">CBOR encoding:<a href="#section-6.13.2-16" class="pilcrow">¶</a></p>
<div id="section-6.13.2-17">
<pre class="lang-cbor-pretty sourcecode">
78 6B
   2F696574662D73797374656D3A73797374656D2F61757468656E74696361
   74696F6E2F757365725B6E616D653D27626F62275D2F617574686F72697A
   65642D6B65795B6E616D653D2761646D696E275D5B636F756E7472793D27
   6672616E6365275D2F6B65792D64617461
</pre><a href="#section-6.13.2-17" class="pilcrow">¶</a>
</div>
<p id="section-6.13.2-18"><strong>Third example:</strong><a href="#section-6.13.2-18" class="pilcrow">¶</a></p>
<p id="section-6.13.2-19">This example is described in <a href="#instance-identifier-with-sid" class="xref">Section 6.13.1</a>.<a href="#section-6.13.2-19" class="pilcrow">¶</a></p>
<p id="section-6.13.2-20">CBOR diagnostic notation:<a href="#section-6.13.2-20" class="pilcrow">¶</a></p>
<div id="section-6.13.2-21">
<pre class="lang-cbor-diag sourcecode">
"/ietf-system:system/authentication/user[name='jack']"
</pre><a href="#section-6.13.2-21" class="pilcrow">¶</a>
</div>
<p id="section-6.13.2-22">CBOR encoding:<a href="#section-6.13.2-22" class="pilcrow">¶</a></p>
<div id="section-6.13.2-23">
<pre class="lang-cbor-pretty sourcecode">
78 34                                   # text(52)
   2F696574662D73797374656D3A73797374656D2F61757468656E74696361
   74696F6E2F757365725B6E616D653D276A61636B275D
</pre><a href="#section-6.13.2-23" class="pilcrow">¶</a>
</div>
</section>
</div>
</section>
</div>
</section>
</div>
<div id="content-type">
<section id="section-7">
      <h2 id="name-content-types">
<a href="#section-7" class="section-number selfRef">7. </a><a href="#name-content-types" class="section-name selfRef">Content-Types</a>
      </h2>
<p id="section-7-1">This specification defines the media type
<code>application/yang-data+cbor</code>, which can be used without parameters or
with the <code>id</code> parameter set to either <code>name</code> or <code>sid</code>.<a href="#section-7-1" class="pilcrow">¶</a></p>
<p id="section-7-2">This media type represents a YANG-CBOR document containing a representation tree.
If the media type parameter <code>id</code> is present,
depending on its value,
each representation node is identified by its associated namespace-qualified
name, as defined in <a href="#name" class="xref">Section 3.3</a> (<code>id=name</code>), or by its associated YANG SID
(represented, e.g., in CBOR map keys as a SID delta or via tag number 47), as defined in <a href="#sid" class="xref">Section 3.2</a>
(<code>id=sid</code>), respectively.
If no <code>id</code> parameter is given, both forms may be present.<a href="#section-7-2" class="pilcrow">¶</a></p>
<p id="section-7-3">The format of an <code>application/yang-data+cbor</code> representation is that
of a CBOR map, mapping names, and/or SIDs (as defined above) into
instance values (using the rules defined in <a href="#instance-encoding" class="xref">Section 4</a>).<a href="#section-7-3" class="pilcrow">¶</a></p>
<p id="section-7-4">It is not foreseen at this point that the valid set of values for the
<code>id</code> parameter will extend beyond <code>name</code>, <code>sid</code>, or being unset; if
that does happen, any new value is foreseen to be of the form
<code>[a-z][a-z0-9]*(-[a-z0-9]+)*</code>.<a href="#section-7-4" class="pilcrow">¶</a></p>
<p id="section-7-5">In summary, this document defines three content-types, which are
intended for use by different classes of applications:<a href="#section-7-5" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-7-6.1">
          <code>application/yang-data+cbor; id=sid</code> -- for use by applications that
need to be frugal with encoding space and text string processing
(e.g., applications running on constrained nodes <span>[<a href="#RFC7228" class="xref">RFC7228</a>]</span> or
applications with particular performance requirements);<a href="#section-7-6.1" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-7-6.2">
          <code>application/yang-data+cbor; id=name</code> -- for use by applications that
do not want to engage in SID management and that have ample
resources to manage text-string-based item identifiers (e.g.,
applications that directly want to substitute
<code>application/yang.data+json</code> with a more efficient representation
without any other changes); and<a href="#section-7-6.2" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-7-6.3">
          <code>application/yang-data+cbor</code> -- for use by more complex applications
that can benefit from the increased efficiency of SID identifiers
but also need to integrate databases of YANG modules before SID
mappings are defined for them.<a href="#section-7-6.3" class="pilcrow">¶</a>
</li>
      </ul>
<p id="section-7-7">All three content-types are based on the same representation
mechanisms, parts of which are simply not used in the first and second
cases.<a href="#section-7-7" class="pilcrow">¶</a></p>
<p id="section-7-8">How the use of one of these content-types is selected in a transfer
protocol is outside the scope of this specification.
The last paragraph of <span><a href="https://www.rfc-editor.org/rfc/rfc8040#section-5.2" class="relref">Section 5.2</a> of [<a href="#RFC8040" class="xref">RFC8040</a>]</span> discusses how to
indicate and request the usage of specific content-types in RESTCONF.
Similar mechanisms are available in the Constrained Application Protocol (CoAP) <span>[<a href="#RFC7252" class="xref">RFC7252</a>]</span> using the
Content-Format and Accept Options; <span>[<a href="#I-D.ietf-core-comi" class="xref">CORE-COMI</a>]</span> demonstrates specifics on
how Content-Format may be used to indicate the <code>id=sid</code> case.<a href="#section-7-8" class="pilcrow">¶</a></p>
</section>
</div>
<div id="security-considerations">
<section id="section-8">
      <h2 id="name-security-considerations">
<a href="#section-8" class="section-number selfRef">8. </a><a href="#name-security-considerations" class="section-name selfRef">Security Considerations</a>
      </h2>
<p id="section-8-1">The security considerations of <span>[<a href="#RFC8949" class="xref">RFC8949</a>]</span> and <span>[<a href="#RFC7950" class="xref">RFC7950</a>]</span> apply.<a href="#section-8-1" class="pilcrow">¶</a></p>
<p id="section-8-2">This document defines an alternative encoding for data modeled in the YANG data modeling language. As such, this encoding does not contribute any new security issues in addition to those identified for the specific protocol or context for which it is used.<a href="#section-8-2" class="pilcrow">¶</a></p>
<p id="section-8-3">To minimize security risks, software on the receiving side <span class="bcp14">SHOULD</span> reject all messages that do not comply to the rules of this document and reply with an appropriate error message to the sender.<a href="#section-8-3" class="pilcrow">¶</a></p>
<p id="section-8-4">For instance, when the <code>id</code> parameter to the media type is used, it is
important to properly reject identifiers of the other type to avoid
scenarios where different implementations interpret a given content in
different ways.<a href="#section-8-4" class="pilcrow">¶</a></p>
<p id="section-8-5">When SIDs are in use, the interpretation of encoded data not only
relies on having the right YANG modules but also on having the right
SID mapping information.  Management and evolution of that mapping
information therefore requires the same care as the management and
evolution of the YANG modules themselves.  The procedures in
<span>[<a href="#I-D.ietf-core-sid" class="xref">CORE-SID</a>]</span> are being defined with this in mind.<a href="#section-8-5" class="pilcrow">¶</a></p>
</section>
</div>
<div id="iana-considerations">
<section id="section-9">
      <h2 id="name-iana-considerations">
<a href="#section-9" class="section-number selfRef">9. </a><a href="#name-iana-considerations" class="section-name selfRef">IANA Considerations</a>
      </h2>
<div id="media-types-registry">
<section id="section-9.1">
        <h3 id="name-media-types-registry">
<a href="#section-9.1" class="section-number selfRef">9.1. </a><a href="#name-media-types-registry" class="section-name selfRef">Media Types Registry</a>
        </h3>
<p id="section-9.1-1">IANA has added the following media type to the "<a href="https://www.iana.org/assignments/media-types/#media-types" class="relref">Media Types</a>" registry <span>[<a href="#IANA.media-types" class="xref">IANA.media-types</a>]</span>.<a href="#section-9.1-1" class="pilcrow">¶</a></p>
<span id="name-media-types-registry-2"></span><table class="left" id="table-2">
          <caption>
<a href="#table-2" class="selfRef">Table 2</a>:
<a href="#name-media-types-registry-2" class="selfRef">Media Types Registry</a>
          </caption>
<thead>
            <tr>
              <th class="text-left" rowspan="1" colspan="1">Name</th>
              <th class="text-left" rowspan="1" colspan="1">Template</th>
              <th class="text-left" rowspan="1" colspan="1">Reference</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">yang-data+cbor</td>
              <td class="text-left" rowspan="1" colspan="1">application/yang-data+cbor</td>
              <td class="text-left" rowspan="1" colspan="1">RFC 9254</td>
            </tr>
          </tbody>
        </table>
<span class="break"></span><dl class="dlParallel" id="section-9.1-3">
          <dt id="section-9.1-3.1">Type name:</dt>
          <dd style="margin-left: 1.5em" id="section-9.1-3.2">application<a href="#section-9.1-3.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-9.1-3.3">Subtype name:</dt>
          <dd style="margin-left: 1.5em" id="section-9.1-3.4">yang-data+cbor<a href="#section-9.1-3.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-9.1-3.5">Required parameters:</dt>
          <dd style="margin-left: 1.5em" id="section-9.1-3.6">N/A<a href="#section-9.1-3.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-9.1-3.7">Optional parameters:</dt>
          <dd style="margin-left: 1.5em" id="section-9.1-3.8">id (see <a href="#content-type" class="xref">Section 7</a> of RFC 9254)<a href="#section-9.1-3.8" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-9.1-3.9">Encoding considerations:</dt>
          <dd style="margin-left: 1.5em" id="section-9.1-3.10">binary (CBOR)<a href="#section-9.1-3.10" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-9.1-3.11">Security considerations:</dt>
          <dd style="margin-left: 1.5em" id="section-9.1-3.12">see <a href="#security-considerations" class="xref">Section 8</a> of RFC 9254<a href="#section-9.1-3.12" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-9.1-3.13">Interoperability considerations:</dt>
          <dd style="margin-left: 1.5em" id="section-9.1-3.14">N/A<a href="#section-9.1-3.14" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-9.1-3.15">Published specification:</dt>
          <dd style="margin-left: 1.5em" id="section-9.1-3.16">RFC 9254<a href="#section-9.1-3.16" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-9.1-3.17">Applications that use this media type:</dt>
          <dd style="margin-left: 1.5em" id="section-9.1-3.18">applications that need a 
   concise and efficient representation of YANG-modeled data<a href="#section-9.1-3.18" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-9.1-3.19">Fragment identifier considerations:</dt>
          <dd style="margin-left: 1.5em" id="section-9.1-3.20">The syntax and semantics of
 fragment identifiers specified for "application/yang-data+cbor" is
 as specified for "application/cbor".  (At publication of this
 document, there is no fragment identification syntax defined for
   "application/cbor".)<a href="#section-9.1-3.20" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-9.1-3.21">Additional information:</dt>
          <dd style="margin-left: 1.5em" id="section-9.1-3.22"></dd>
          <dd class="break"></dd>
<dt id="section-9.1-3.23">Magic number(s):</dt>
          <dd style="margin-left: 1.5em" id="section-9.1-3.24">N/A<a href="#section-9.1-3.24" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-9.1-3.25">File extension(s):</dt>
          <dd style="margin-left: 1.5em" id="section-9.1-3.26">N/A<a href="#section-9.1-3.26" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-9.1-3.27">Macintosh file type code(s):</dt>
          <dd style="margin-left: 1.5em" id="section-9.1-3.28">N/A<a href="#section-9.1-3.28" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-9.1-3.29">Person &amp; email address to contact for further information:</dt>
          <dd style="margin-left: 1.5em" id="section-9.1-3.30">CORE WG mailing list (core@ietf.org)
   or IETF Applications and Real-Time Area (art@ietf.org)<a href="#section-9.1-3.30" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-9.1-3.31">Intended usage:</dt>
          <dd style="margin-left: 1.5em" id="section-9.1-3.32">COMMON<a href="#section-9.1-3.32" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-9.1-3.33">Restrictions on usage:</dt>
          <dd style="margin-left: 1.5em" id="section-9.1-3.34">N/A<a href="#section-9.1-3.34" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-9.1-3.35">Author:</dt>
          <dd style="margin-left: 1.5em" id="section-9.1-3.36">CoRE WG<a href="#section-9.1-3.36" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-9.1-3.37">Change controller:</dt>
          <dd style="margin-left: 1.5em" id="section-9.1-3.38">IETF<a href="#section-9.1-3.38" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
</section>
</div>
<div id="coap-content-formats-registry">
<section id="section-9.2">
        <h3 id="name-coap-content-formats-regist">
<a href="#section-9.2" class="section-number selfRef">9.2. </a><a href="#name-coap-content-formats-regist" class="section-name selfRef">CoAP Content-Formats Registry</a>
        </h3>
<p id="section-9.2-1">IANA has added the following Content-Formats to the "<a href="https://www.iana.org/assignments/core-parameters/#content-formats" class="relref">CoAP Content-Formats</a>" subregistry,
within the "<a href="https://www.iana.org/assignments/core-parameters/#coap-content-format" class="relref">Constrained RESTful Environments (CoRE) Parameters</a>"
registry <span>[<a href="#IANA.core-parameters" class="xref">IANA.core-parameters</a>]</span>. The registration procedure is "Expert Review" for the 0-255 range and
"IETF Review" for the 256-9999 range.<a href="#section-9.2-1" class="pilcrow">¶</a></p>
<span id="name-coap-content-format-registr"></span><table class="left" id="table-3">
          <caption>
<a href="#table-3" class="selfRef">Table 3</a>:
<a href="#name-coap-content-format-registr" class="selfRef">CoAP Content-Format Registry</a>
          </caption>
<thead>
            <tr>
              <th class="text-left" rowspan="1" colspan="1">Media Type</th>
              <th class="text-left" rowspan="1" colspan="1">Encoding</th>
              <th class="text-left" rowspan="1" colspan="1">ID</th>
              <th class="text-left" rowspan="1" colspan="1">Reference</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">application/yang-data+cbor</td>
              <td class="text-left" rowspan="1" colspan="1">-</td>
              <td class="text-left" rowspan="1" colspan="1">340</td>
              <td class="text-left" rowspan="1" colspan="1">RFC 9254</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">application/yang-data+cbor; id=name</td>
              <td class="text-left" rowspan="1" colspan="1">-</td>
              <td class="text-left" rowspan="1" colspan="1">341</td>
              <td class="text-left" rowspan="1" colspan="1">RFC 9254</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">application/yang-data+cbor; id=sid</td>
              <td class="text-left" rowspan="1" colspan="1">-</td>
              <td class="text-left" rowspan="1" colspan="1">140</td>
              <td class="text-left" rowspan="1" colspan="1">RFC 9254</td>
            </tr>
          </tbody>
        </table>
</section>
</div>
<div id="tag-registry">
<section id="section-9.3">
        <h3 id="name-cbor-tags-registry">
<a href="#section-9.3" class="section-number selfRef">9.3. </a><a href="#name-cbor-tags-registry" class="section-name selfRef">CBOR Tags Registry</a>
        </h3>
<p id="section-9.3-1">IANA has allocated the following CBOR tag numbers in the "<a href="https://www.iana.org/assignments/cbor-tags#tags" class="relref">CBOR Tags</a>" registry <span>[<a href="#IANA.cbor-tags" class="xref">IANA.cbor-tags</a>]</span> defined in  <span><a href="https://www.rfc-editor.org/rfc/rfc8949#section-9.2" class="relref">Section 9.2</a> of [<a href="#RFC8949" class="xref">RFC8949</a>]</span>.<a href="#section-9.3-1" class="pilcrow">¶</a></p>
<span id="name-cbor-tags-registry-2"></span><div id="tab-tag-values">
<table class="center" id="table-4">
          <caption>
<a href="#table-4" class="selfRef">Table 4</a>:
<a href="#name-cbor-tags-registry-2" class="selfRef">CBOR Tags Registry</a>
          </caption>
<thead>
            <tr>
              <th class="text-left" rowspan="1" colspan="1">Tag</th>
              <th class="text-left" rowspan="1" colspan="1">Data Item</th>
              <th class="text-left" rowspan="1" colspan="1">Semantics</th>
              <th class="text-left" rowspan="1" colspan="1">Reference</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">43</td>
              <td class="text-left" rowspan="1" colspan="1">text string</td>
              <td class="text-left" rowspan="1" colspan="1">YANG bits datatype; see <a href="#bits" class="xref">Section 6.7</a>.</td>
              <td class="text-left" rowspan="1" colspan="1">RFC 9254</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">44</td>
              <td class="text-left" rowspan="1" colspan="1">text string</td>
              <td class="text-left" rowspan="1" colspan="1">YANG enumeration datatype; see <a href="#enumeration" class="xref">Section 6.6</a>.</td>
              <td class="text-left" rowspan="1" colspan="1">RFC 9254</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">45</td>
              <td class="text-left" rowspan="1" colspan="1">unsigned integer or text string</td>
              <td class="text-left" rowspan="1" colspan="1">YANG identityref datatype; see <a href="#identityref" class="xref">Section 6.10</a>.</td>
              <td class="text-left" rowspan="1" colspan="1">RFC 9254</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">46</td>
              <td class="text-left" rowspan="1" colspan="1">unsigned integer or text string or array</td>
              <td class="text-left" rowspan="1" colspan="1">YANG instance-identifier datatype; see <a href="#instance-id" class="xref">Section 6.13</a>.</td>
              <td class="text-left" rowspan="1" colspan="1">RFC 9254</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">47</td>
              <td class="text-left" rowspan="1" colspan="1">unsigned integer</td>
              <td class="text-left" rowspan="1" colspan="1">YANG Schema Item iDentifier (SID); see <a href="#sid" class="xref">Section 3.2</a>.</td>
              <td class="text-left" rowspan="1" colspan="1">RFC 9254</td>
            </tr>
          </tbody>
        </table>
</div>
</section>
</div>
</section>
</div>
<section id="section-10">
      <h2 id="name-references">
<a href="#section-10" class="section-number selfRef">10. </a><a href="#name-references" class="section-name selfRef">References</a>
      </h2>
<section id="section-10.1">
        <h3 id="name-normative-references">
<a href="#section-10.1" class="section-number selfRef">10.1. </a><a href="#name-normative-references" class="section-name selfRef">Normative References</a>
        </h3>
<dl class="references">
<dt id="IANA.cbor-tags">[IANA.cbor-tags]</dt>
        <dd>
<span class="refAuthor">IANA</span>, <span class="refTitle">"Concise Binary Object Representation (CBOR) Tags"</span>, <span>&lt;<a href="https://www.iana.org/assignments/cbor-tags">https://www.iana.org/assignments/cbor-tags</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="IANA.core-parameters">[IANA.core-parameters]</dt>
        <dd>
<span class="refAuthor">IANA</span>, <span class="refTitle">"Constrained RESTful Environments (CoRE) Parameters"</span>, <span>&lt;<a href="https://www.iana.org/assignments/core-parameters/">https://www.iana.org/assignments/core-parameters/</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="IANA.media-types">[IANA.media-types]</dt>
        <dd>
<span class="refAuthor">IANA</span>, <span class="refTitle">"Media Types"</span>, <span>&lt;<a href="https://www.iana.org/assignments/media-types/">https://www.iana.org/assignments/media-types/</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC2119">[RFC2119]</dt>
        <dd>
<span class="refAuthor">Bradner, S.</span>, <span class="refTitle">"Key words for use in RFCs to Indicate Requirement Levels"</span>, <span class="seriesInfo">BCP 14</span>, <span class="seriesInfo">RFC 2119</span>, <span class="seriesInfo">DOI 10.17487/RFC2119</span>, <time datetime="1997-03" class="refDate">March 1997</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc2119">https://www.rfc-editor.org/info/rfc2119</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC5234">[RFC5234]</dt>
        <dd>
<span class="refAuthor">Crocker, D., Ed.</span> and <span class="refAuthor">P. Overell</span>, <span class="refTitle">"Augmented BNF for Syntax Specifications: ABNF"</span>, <span class="seriesInfo">STD 68</span>, <span class="seriesInfo">RFC 5234</span>, <span class="seriesInfo">DOI 10.17487/RFC5234</span>, <time datetime="2008-01" class="refDate">January 2008</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc5234">https://www.rfc-editor.org/info/rfc5234</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7950">[RFC7950]</dt>
        <dd>
<span class="refAuthor">Bjorklund, M., Ed.</span>, <span class="refTitle">"The YANG 1.1 Data Modeling Language"</span>, <span class="seriesInfo">RFC 7950</span>, <span class="seriesInfo">DOI 10.17487/RFC7950</span>, <time datetime="2016-08" class="refDate">August 2016</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7950">https://www.rfc-editor.org/info/rfc7950</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7951">[RFC7951]</dt>
        <dd>
<span class="refAuthor">Lhotka, L.</span>, <span class="refTitle">"JSON Encoding of Data Modeled with YANG"</span>, <span class="seriesInfo">RFC 7951</span>, <span class="seriesInfo">DOI 10.17487/RFC7951</span>, <time datetime="2016-08" class="refDate">August 2016</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7951">https://www.rfc-editor.org/info/rfc7951</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8040">[RFC8040]</dt>
        <dd>
<span class="refAuthor">Bierman, A.</span>, <span class="refAuthor">Bjorklund, M.</span>, and <span class="refAuthor">K. Watsen</span>, <span class="refTitle">"RESTCONF Protocol"</span>, <span class="seriesInfo">RFC 8040</span>, <span class="seriesInfo">DOI 10.17487/RFC8040</span>, <time datetime="2017-01" class="refDate">January 2017</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8040">https://www.rfc-editor.org/info/rfc8040</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8174">[RFC8174]</dt>
        <dd>
<span class="refAuthor">Leiba, B.</span>, <span class="refTitle">"Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words"</span>, <span class="seriesInfo">BCP 14</span>, <span class="seriesInfo">RFC 8174</span>, <span class="seriesInfo">DOI 10.17487/RFC8174</span>, <time datetime="2017-05" class="refDate">May 2017</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8174">https://www.rfc-editor.org/info/rfc8174</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8259">[RFC8259]</dt>
        <dd>
<span class="refAuthor">Bray, T., Ed.</span>, <span class="refTitle">"The JavaScript Object Notation (JSON) Data Interchange Format"</span>, <span class="seriesInfo">STD 90</span>, <span class="seriesInfo">RFC 8259</span>, <span class="seriesInfo">DOI 10.17487/RFC8259</span>, <time datetime="2017-12" class="refDate">December 2017</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8259">https://www.rfc-editor.org/info/rfc8259</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8610">[RFC8610]</dt>
        <dd>
<span class="refAuthor">Birkholz, H.</span>, <span class="refAuthor">Vigano, C.</span>, and <span class="refAuthor">C. Bormann</span>, <span class="refTitle">"Concise Data Definition Language (CDDL): A Notational Convention to Express Concise Binary Object Representation (CBOR) and JSON Data Structures"</span>, <span class="seriesInfo">RFC 8610</span>, <span class="seriesInfo">DOI 10.17487/RFC8610</span>, <time datetime="2019-06" class="refDate">June 2019</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8610">https://www.rfc-editor.org/info/rfc8610</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8791">[RFC8791]</dt>
        <dd>
<span class="refAuthor">Bierman, A.</span>, <span class="refAuthor">Björklund, M.</span>, and <span class="refAuthor">K. Watsen</span>, <span class="refTitle">"YANG Data Structure Extensions"</span>, <span class="seriesInfo">RFC 8791</span>, <span class="seriesInfo">DOI 10.17487/RFC8791</span>, <time datetime="2020-06" class="refDate">June 2020</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8791">https://www.rfc-editor.org/info/rfc8791</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8949">[RFC8949]</dt>
      <dd>
<span class="refAuthor">Bormann, C.</span> and <span class="refAuthor">P. Hoffman</span>, <span class="refTitle">"Concise Binary Object Representation (CBOR)"</span>, <span class="seriesInfo">STD 94</span>, <span class="seriesInfo">RFC 8949</span>, <span class="seriesInfo">DOI 10.17487/RFC8949</span>, <time datetime="2020-12" class="refDate">December 2020</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8949">https://www.rfc-editor.org/info/rfc8949</a>&gt;</span>. </dd>
<dd class="break"></dd>
</dl>
</section>
<section id="section-10.2">
        <h3 id="name-informative-references">
<a href="#section-10.2" class="section-number selfRef">10.2. </a><a href="#name-informative-references" class="section-name selfRef">Informative References</a>
        </h3>
<dl class="references">
<dt id="I-D.ietf-core-comi">[CORE-COMI]</dt>
        <dd>
<span class="refAuthor">Veillette, M., Ed.</span>, <span class="refAuthor">van der Stok, P., Ed.</span>, <span class="refAuthor">Pelov, A.</span>, <span class="refAuthor">Bierman, A.</span>, and <span class="refAuthor">I. Petrov, Ed.</span>, <span class="refTitle">"CoAP Management Interface (CORECONF)"</span>, <span class="refContent">Work in Progress</span>, <span class="seriesInfo">Internet-Draft, draft-ietf-core-comi-11</span>, <time datetime="2021-01-17" class="refDate">17 January 2021</time>, <span>&lt;<a href="https://datatracker.ietf.org/doc/html/draft-ietf-core-comi-11">https://datatracker.ietf.org/doc/html/draft-ietf-core-comi-11</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="I-D.ietf-core-sid">[CORE-SID]</dt>
        <dd>
<span class="refAuthor">Veillette, M., Ed.</span>, <span class="refAuthor">Pelov, A., Ed.</span>, <span class="refAuthor">Petrov, I., Ed.</span>, <span class="refAuthor">Bormann, C.</span>, and <span class="refAuthor">M. Richardson</span>, <span class="refTitle">"YANG Schema Item iDentifier (YANG SID)"</span>, <span class="refContent">Work in Progress</span>, <span class="seriesInfo">Internet-Draft, draft-ietf-core-sid-18</span>, <time datetime="2021-11-18" class="refDate">18 November 2021</time>, <span>&lt;<a href="https://datatracker.ietf.org/doc/html/draft-ietf-core-sid-18">https://datatracker.ietf.org/doc/html/draft-ietf-core-sid-18</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6241">[RFC6241]</dt>
        <dd>
<span class="refAuthor">Enns, R., Ed.</span>, <span class="refAuthor">Bjorklund, M., Ed.</span>, <span class="refAuthor">Schoenwaelder, J., Ed.</span>, and <span class="refAuthor">A. Bierman, Ed.</span>, <span class="refTitle">"Network Configuration Protocol (NETCONF)"</span>, <span class="seriesInfo">RFC 6241</span>, <span class="seriesInfo">DOI 10.17487/RFC6241</span>, <time datetime="2011-06" class="refDate">June 2011</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6241">https://www.rfc-editor.org/info/rfc6241</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6991">[RFC6991]</dt>
        <dd>
<span class="refAuthor">Schoenwaelder, J., Ed.</span>, <span class="refTitle">"Common YANG Data Types"</span>, <span class="seriesInfo">RFC 6991</span>, <span class="seriesInfo">DOI 10.17487/RFC6991</span>, <time datetime="2013-07" class="refDate">July 2013</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6991">https://www.rfc-editor.org/info/rfc6991</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7228">[RFC7228]</dt>
        <dd>
<span class="refAuthor">Bormann, C.</span>, <span class="refAuthor">Ersue, M.</span>, and <span class="refAuthor">A. Keranen</span>, <span class="refTitle">"Terminology for Constrained-Node Networks"</span>, <span class="seriesInfo">RFC 7228</span>, <span class="seriesInfo">DOI 10.17487/RFC7228</span>, <time datetime="2014-05" class="refDate">May 2014</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7228">https://www.rfc-editor.org/info/rfc7228</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7252">[RFC7252]</dt>
        <dd>
<span class="refAuthor">Shelby, Z.</span>, <span class="refAuthor">Hartke, K.</span>, and <span class="refAuthor">C. Bormann</span>, <span class="refTitle">"The Constrained Application Protocol (CoAP)"</span>, <span class="seriesInfo">RFC 7252</span>, <span class="seriesInfo">DOI 10.17487/RFC7252</span>, <time datetime="2014-06" class="refDate">June 2014</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7252">https://www.rfc-editor.org/info/rfc7252</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7317">[RFC7317]</dt>
        <dd>
<span class="refAuthor">Bierman, A.</span> and <span class="refAuthor">M. Bjorklund</span>, <span class="refTitle">"A YANG Data Model for System Management"</span>, <span class="seriesInfo">RFC 7317</span>, <span class="seriesInfo">DOI 10.17487/RFC7317</span>, <time datetime="2014-08" class="refDate">August 2014</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7317">https://www.rfc-editor.org/info/rfc7317</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8343">[RFC8343]</dt>
        <dd>
<span class="refAuthor">Bjorklund, M.</span>, <span class="refTitle">"A YANG Data Model for Interface Management"</span>, <span class="seriesInfo">RFC 8343</span>, <span class="seriesInfo">DOI 10.17487/RFC8343</span>, <time datetime="2018-03" class="refDate">March 2018</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8343">https://www.rfc-editor.org/info/rfc8343</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8344">[RFC8344]</dt>
      <dd>
<span class="refAuthor">Bjorklund, M.</span>, <span class="refTitle">"A YANG Data Model for IP Management"</span>, <span class="seriesInfo">RFC 8344</span>, <span class="seriesInfo">DOI 10.17487/RFC8344</span>, <time datetime="2018-03" class="refDate">March 2018</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8344">https://www.rfc-editor.org/info/rfc8344</a>&gt;</span>. </dd>
<dd class="break"></dd>
</dl>
</section>
</section>
<div id="acknowledgments">
<section id="appendix-A">
      <h2 id="name-acknowledgments">
<a href="#name-acknowledgments" class="section-name selfRef">Acknowledgments</a>
      </h2>
<p id="appendix-A-1">This document has been largely inspired by the extensive work done by <span class="contact-name">Andy Bierman</span> and <span class="contact-name">Peter van der Stok</span> on <span>[<a href="#I-D.ietf-core-comi" class="xref">CORE-COMI</a>]</span>. <span>[<a href="#RFC7951" class="xref">RFC7951</a>]</span> has also been a critical input to this work. The authors would like to thank the authors and contributors of these two documents.<a href="#appendix-A-1" class="pilcrow">¶</a></p>
<p id="appendix-A-2">The authors would also like to acknowledge the review, feedback, and
comments from <span class="contact-name">Ladislav Lhotka</span> and <span class="contact-name">Jürgen Schönwälder</span> and from the
Document Shepherd <span class="contact-name">Marco Tiloca</span>.
Extensive comments helped us further improve the document in the IESG
review process; the authors would like to call out specifically the
feedback and guidance by the responsible AD <span class="contact-name">Francesca Palombini</span> and
the significant improvements suggested by IESG members <span class="contact-name">Benjamin Kaduk</span>
and <span class="contact-name">Rob Wilton</span>.<a href="#appendix-A-2" class="pilcrow">¶</a></p>
</section>
</div>
<div id="authors-addresses">
<section id="appendix-B">
      <h2 id="name-authors-addresses">
<a href="#name-authors-addresses" class="section-name selfRef">Authors' Addresses</a>
      </h2>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Michel Veillette (<span class="role">editor</span>)</span></div>
<div dir="auto" class="left"><span class="org">Trilliant Networks Inc.</span></div>
<div dir="auto" class="left"><span class="street-address">610 Rue du Luxembourg</span></div>
<div dir="auto" class="left">
<span class="locality">Granby</span> <span class="region">Quebec</span> <span class="postal-code">J2J 2V2</span>
</div>
<div dir="auto" class="left"><span class="country-name">Canada</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:michel.veillette@trilliantinc.com" class="email">michel.veillette@trilliantinc.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Ivaylo Petrov (<span class="role">editor</span>)</span></div>
<div dir="auto" class="left"><span class="org">Google Switzerland GmbH</span></div>
<div dir="auto" class="left"><span class="street-address">Brandschenkestrasse 110</span></div>
<div dir="auto" class="left">CH-<span class="postal-code">8002</span> <span class="locality">Zurich</span>
</div>
<div dir="auto" class="left"><span class="country-name">Switzerland</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:ivaylopetrov@google.com" class="email">ivaylopetrov@google.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Alexander Pelov</span></div>
<div dir="auto" class="left"><span class="org">Acklio</span></div>
<div dir="auto" class="left"><span class="street-address">1137A avenue des Champs Blancs</span></div>
<div dir="auto" class="left">
<span class="postal-code">35510</span> <span class="locality">Cesson-Sevigne Cedex</span>
</div>
<div dir="auto" class="left"><span class="country-name">France</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:a@ackl.io" class="email">a@ackl.io</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Carsten Bormann</span></div>
<div dir="auto" class="left"><span class="org">Universität Bremen TZI</span></div>
<div dir="auto" class="left"><span class="street-address">Postfach 330440</span></div>
<div dir="auto" class="left">
<span class="postal-code">D-28359</span> <span class="locality">Bremen</span>
</div>
<div dir="auto" class="left"><span class="country-name">Germany</span></div>
<div class="tel">
<span>Phone:</span>
<a href="tel:+49-421-218-63921" class="tel">+49-421-218-63921</a>
</div>
<div class="email">
<span>Email:</span>
<a href="mailto:cabo@tzi.org" class="email">cabo@tzi.org</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Michael Richardson</span></div>
<div dir="auto" class="left"><span class="org">Sandelman Software Works</span></div>
<div dir="auto" class="left"><span class="country-name">Canada</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:mcr+ietf@sandelman.ca" class="email">mcr+ietf@sandelman.ca</a>
</div>
</address>
</section>
</div>
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