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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 8917: The LoST-Validation Straightforward-Naming Authority PoinTeR (S-NAPTR) Application Service Tag</title>
<meta content="Randall Gellens" name="author">
<meta content="Brian Rosen" name="author">
<meta content="
       This document adds the 'LoST-Validation' service tag to the
      Straightforward-Naming Authority PoinTeR (S-NAPTR) Application Service
      Tag IANA registry.  This tag can appear in a Naming Authority Pointer
      (NAPTR) Domain Name System (DNS) record to assist clients of the
      Location-to-Service Translation (LoST) Protocol in identifying LoST
      servers designated for location validation.  This tag and
      the information about its use update RFC 5222, which enables the explicit discovery of a server that supports location validation. 
    " name="description">
<meta content="xml2rfc 3.3.0" name="generator">
<meta content="location" name="keyword">
<meta content="LoST" name="keyword">
<meta content="emergency" name="keyword">
<meta content="emergency services" name="keyword">
<meta content="ecrf" name="keyword">
<meta content="lvf" name="keyword">
<meta content="i3" name="keyword">
<meta content="8917" name="rfc.number">
<!-- Generator version information:
  xml2rfc 3.3.0
    Python 3.6.10
    appdirs 1.4.4
    ConfigArgParse 1.2.3
    google-i18n-address 2.3.5
    html5lib 1.0.1
    intervaltree 3.0.2
    Jinja2 2.11.2
    kitchen 1.2.6
    lxml 4.4.2
    pycairo 1.19.0
    pycountry 19.8.18
    pyflakes 2.1.1
    PyYAML 5.3.1
    requests 2.22.0
    setuptools 40.6.2
    six 1.14.0
    WeasyPrint 51
-->
<link href="rfc8917.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 {
  zoom: 1.0;
  width: extend-to-zoom;
}
@-ms-viewport {
  width: extend-to-zoom;
  zoom: 1.0;
}
/* general and mobile first */
html {
}
body {
  max-width: 90%;
  margin: 1.5em auto;
  color: #222;
  background-color: #fff;
  font-size: 14px;
  font-family: 'Noto Sans', Arial, Helvetica, sans-serif;
  line-height: 1.6;
  scroll-behavior: smooth;
}
.ears {
  display: none;
}

/* headings */
#title, h1, h2, h3, h4, h5, h6 {
  margin: 1em 0 0.5em;
  font-weight: bold;
  line-height: 1.3;
}
#title {
  clear: both;
  border-bottom: 1px solid #ddd;
  margin: 0 0 0.5em 0;
  padding: 1em 0 0.5em;
}
.author {
  padding-bottom: 4px;
}
h1 {
  font-size: 26px;
  margin: 1em 0;
}
h2 {
  font-size: 22px;
  margin-top: -20px;  /* provide offset for in-page anchors */
  padding-top: 33px;
}
h3 {
  font-size: 18px;
  margin-top: -36px;  /* provide offset for in-page anchors */
  padding-top: 42px;
}
h4 {
  font-size: 16px;
  margin-top: -36px;  /* provide offset for in-page anchors */
  padding-top: 42px;
}
h5, h6 {
  font-size: 14px;
}
#n-copyright-notice {
  border-bottom: 1px solid #ddd;
  padding-bottom: 1em;
  margin-bottom: 1em;
}
/* general structure */
p {
  padding: 0;
  margin: 0 0 1em 0;
  text-align: left;
}
div, span {
  position: relative;
}
div {
  margin: 0;
}
.alignRight.art-text {
  background-color: #f9f9f9;
  border: 1px solid #eee;
  border-radius: 3px;
  padding: 1em 1em 0;
  margin-bottom: 1.5em;
}
.alignRight.art-text pre {
  padding: 0;
}
.alignRight {
  margin: 1em 0;
}
.alignRight > *:first-child {
  border: none;
  margin: 0;
  float: right;
  clear: both;
}
.alignRight > *:nth-child(2) {
  clear: both;
  display: block;
  border: none;
}
svg {
  display: block;
}
.alignCenter.art-text {
  background-color: #f9f9f9;
  border: 1px solid #eee;
  border-radius: 3px;
  padding: 1em 1em 0;
  margin-bottom: 1.5em;
}
.alignCenter.art-text pre {
  padding: 0;
}
.alignCenter {
  margin: 1em 0;
}
.alignCenter > *:first-child {
  border: none;
  /* this isn't optimal, but it's an existence proof.  PrinceXML doesn't
     support flexbox yet.
  */
  display: table;
  margin: 0 auto;
}

/* lists */
ol, ul {
  padding: 0;
  margin: 0 0 1em 2em;
}
ol ol, ul ul, ol ul, ul ol {
  margin-left: 1em;
}
li {
  margin: 0 0 0.25em 0;
}
.ulCompact li {
  margin: 0;
}
ul.empty, .ulEmpty {
  list-style-type: none;
}
ul.empty li, .ulEmpty li {
  margin-top: 0.5em;
}
ul.compact, .ulCompact,
ol.compact, .olCompact {
  line-height: 100%;
  margin: 0 0 0 2em;
}

/* definition lists */
dl {
}
dl > dt {
  float: left;
  margin-right: 1em;
}
/* 
dl.nohang > dt {
  float: none;
}
*/
dl > dd {
  margin-bottom: .8em;
  min-height: 1.3em;
}
dl.compact > dd, .dlCompact > dd {
  margin-bottom: 0em;
}
dl > dd > dl {
  margin-top: 0.5em;
  margin-bottom: 0em;
}

/* links */
a {
  text-decoration: none;
}
a[href] {
  color: #22e; /* Arlen: WCAG 2019 */
}
a[href]:hover {
  background-color: #f2f2f2;
}
figcaption a[href],
a[href].selfRef {
  color: #222;
}
/* XXX probably not this:
a.selfRef:hover {
  background-color: transparent;
  cursor: default;
} */

/* Figures */
tt, code, pre, code {
  background-color: #f9f9f9;
  font-family: 'Roboto Mono', monospace;
}
pre {
  border: 1px solid #eee;
  margin: 0;
  padding: 1em;
}
img {
  max-width: 100%;
}
figure {
  margin: 0;
}
figure blockquote {
  margin: 0.8em 0.4em 0.4em;
}
figcaption {
  font-style: italic;
  margin: 0 0 1em 0;
}
@media screen {
  pre {
    overflow-x: auto;
    max-width: 100%;
    max-width: calc(100% - 22px);
  }
}

/* aside, blockquote */
aside, blockquote {
  margin-left: 0;
  padding: 1.2em 2em;
}
blockquote {
  background-color: #f9f9f9;
  color: #111; /* Arlen: WCAG 2019 */
  border: 1px solid #ddd;
  border-radius: 3px;
  margin: 1em 0;
}
cite {
  display: block;
  text-align: right;
  font-style: italic;
}

/* tables */
table {
  width: 100%;
  margin: 0 0 1em;
  border-collapse: collapse;
  border: 1px solid #eee;
}
th, td {
  text-align: left;
  vertical-align: top;
  padding: 0.5em 0.75em;
}
th {
  text-align: left;
  background-color: #e9e9e9;
}
tr:nth-child(2n+1) > td {
  background-color: #f5f5f5;
}
table caption {
  font-style: italic;
  margin: 0;
  padding: 0;
  text-align: left;
}
table p {
  /* XXX to avoid bottom margin on table row signifiers. If paragraphs should
     be allowed within tables more generally, it would be far better to select on a class. */
  margin: 0;
}

/* pilcrow */
a.pilcrow {
  color: #666; /* Arlen: AHDJ 2019 */
  text-decoration: none;
  visibility: hidden;
  user-select: none;
  -ms-user-select: none;
  -o-user-select:none;
  -moz-user-select: none;
  -khtml-user-select: none;
  -webkit-user-select: none;
  -webkit-touch-callout: none;
}
@media screen {
  aside:hover > a.pilcrow,
  p:hover > a.pilcrow,
  blockquote:hover > a.pilcrow,
  div:hover > a.pilcrow,
  li:hover > a.pilcrow,
  pre:hover > a.pilcrow {
    visibility: visible;
  }
  a.pilcrow:hover {
    background-color: transparent;
  }
}

/* misc */
hr {
  border: 0;
  border-top: 1px solid #eee;
}
.bcp14 {
  font-variant: small-caps;
}

.role {
  font-variant: all-small-caps;
}

/* info block */
#identifiers {
  margin: 0;
  font-size: 0.9em;
}
#identifiers dt {
  width: 3em;
  clear: left;
}
#identifiers dd {
  float: left;
  margin-bottom: 0;
}
#identifiers .authors .author {
  display: inline-block;
  margin-right: 1.5em;
}
#identifiers .authors .org {
  font-style: italic;
}

/* The prepared/rendered info at the very bottom of the page */
.docInfo {
  color: #666; /* Arlen: WCAG 2019 */
  font-size: 0.9em;
  font-style: italic;
  margin-top: 2em;
}
.docInfo .prepared {
  float: left;
}
.docInfo .prepared {
  float: right;
}

/* table of contents */
#toc  {
  padding: 0.75em 0 2em 0;
  margin-bottom: 1em;
}
nav.toc ul {
  margin: 0 0.5em 0 0;
  padding: 0;
  list-style: none;
}
nav.toc li {
  line-height: 1.3em;
  margin: 0.75em 0;
  padding-left: 1.2em;
  text-indent: -1.2em;
}
/* references */
.references dt {
  text-align: right;
  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 {
  margin: 0;
}
.index li {
  margin: 0;
  text-indent: -2em;
  padding-left: 2em;
  padding-bottom: 5px;
}
.indexIndex {
  margin: 0.5em 0 1em;
}
.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 {
    -moz-column-count: 1;
    -moz-column-gap: 0;
  }
}

/* authors */
address.vcard {
  font-style: normal;
  margin: 1em 0;
}

address.vcard .nameRole {
  font-weight: 700;
  margin-left: 0;
}
address.vcard .label {
  font-family: "Noto Sans",Arial,Helvetica,sans-serif;
  margin: 0.5em 0;
}
address.vcard .type {
  display: none;
}
.alternative-contact {
  margin: 1.5em 0 1em;
}
hr.addr {
  border-top: 1px dashed;
  margin: 0;
  color: #ddd;
  max-width: calc(100% - 16px);
}

/* temporary notes */
.rfcEditorRemove::before {
  position: absolute;
  top: 0.2em;
  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 {
  position: relative;
  padding-top: 1.8em;
  background-color: #ffd; /* Arlen: WCAG 2019 */
  border-radius: 3px;
}
.cref {
  background-color: #ffd; /* Arlen: WCAG 2019 */
  padding: 2px 4px;
}
.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;
  }
  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 {
  padding-top: 0;
  @top-left {
    content: normal;
    border: none;
  }
  @top-center {
    content: normal;
    border: none;
  }
  @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;
  }
  @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 {
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<table class="ears">
<thead><tr>
<td class="left">RFC 8917</td>
<td class="center">LoST-Validation</td>
<td class="right">October 2020</td>
</tr></thead>
<tfoot><tr>
<td class="left">Gellens &amp; Rosen</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/rfc8917" class="eref">8917</a></dd>
<dt class="label-updates">Updates:</dt>
<dd class="updates">
<a href="https://www.rfc-editor.org/rfc/rfc5222" class="eref">5222</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="2020-10" class="published">October 2020</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">R. Gellens</div>
<div class="org">Core Technology Consulting</div>
</div>
<div class="author">
      <div class="author-name">B. Rosen</div>
</div>
</dd>
</dl>
</div>
<h1 id="rfcnum">RFC 8917</h1>
<h1 id="title">The LoST-Validation Straightforward-Naming Authority PoinTeR (S-NAPTR) Application Service Tag</h1>
<section id="section-abstract">
      <h2 id="abstract"><a href="#abstract" class="selfRef">Abstract</a></h2>
<p id="section-abstract-1">This document adds the 'LoST-Validation' service tag to the
      Straightforward-Naming Authority PoinTeR (S-NAPTR) Application Service
      Tag IANA registry.  This tag can appear in a Naming Authority Pointer
      (NAPTR) Domain Name System (DNS) record to assist clients of the
      Location-to-Service Translation (LoST) Protocol in identifying LoST
      servers designated for location validation.  This tag and
      the information about its use update RFC 5222, which enables the explicit discovery of a server that supports location validation.<a href="#section-abstract-1" 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/rfc8917">https://www.rfc-editor.org/info/rfc8917</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) 2020 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
            carefully, as they describe your rights and restrictions with
            respect to this document. Code Components extracted from this
            document must include Simplified BSD License text as described in
            Section 4.e of the Trust Legal Provisions and are provided without
            warranty as described in the Simplified 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="ulEmpty toc compact">
<li class="ulEmpty toc compact" 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-document-scope" class="xref">Document Scope</a><a href="#section-toc.1-1.1.1" class="pilcrow">¶</a></p>
</li>
          <li class="ulEmpty toc compact" 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-introduction" class="xref">Introduction</a><a href="#section-toc.1-1.2.1" class="pilcrow">¶</a></p>
<ul class="ulEmpty toc compact">
<li class="ulEmpty toc compact" id="section-toc.1-1.2.2.1">
                <p id="section-toc.1-1.2.2.1.1" class="keepWithNext"><a href="#section-2.1" class="xref">2.1</a>.  <a href="#name-requirements-language" class="xref">Requirements Language</a><a href="#section-toc.1-1.2.2.1.1" class="pilcrow">¶</a></p>
</li>
            </ul>
</li>
          <li class="ulEmpty toc compact" 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-the-lost-validation-applica" class="xref">The LoST-Validation Application Service Tag</a><a href="#section-toc.1-1.3.1" class="pilcrow">¶</a></p>
</li>
          <li class="ulEmpty toc compact" 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-backwards-compatibility" class="xref">Backwards Compatibility</a><a href="#section-toc.1-1.4.1" class="pilcrow">¶</a></p>
</li>
          <li class="ulEmpty toc compact" 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-security-considerations" class="xref">Security Considerations</a><a href="#section-toc.1-1.5.1" class="pilcrow">¶</a></p>
</li>
          <li class="ulEmpty toc compact" 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-iana-considerations" class="xref">IANA Considerations</a><a href="#section-toc.1-1.6.1" class="pilcrow">¶</a></p>
<ul class="ulEmpty toc compact">
<li class="ulEmpty toc compact" 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-s-naptr-registration" class="xref">S-NAPTR Registration</a><a href="#section-toc.1-1.6.2.1.1" class="pilcrow">¶</a></p>
</li>
            </ul>
</li>
          <li class="ulEmpty toc compact" 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-references" class="xref">References</a><a href="#section-toc.1-1.7.1" class="pilcrow">¶</a></p>
<ul class="ulEmpty toc compact">
<li class="ulEmpty toc compact" id="section-toc.1-1.7.2.1">
                <p id="section-toc.1-1.7.2.1.1"><a href="#section-7.1" class="xref">7.1</a>.  <a href="#name-normative-references" class="xref">Normative References</a><a href="#section-toc.1-1.7.2.1.1" class="pilcrow">¶</a></p>
</li>
              <li class="ulEmpty toc compact" id="section-toc.1-1.7.2.2">
                <p id="section-toc.1-1.7.2.2.1"><a href="#section-7.2" class="xref">7.2</a>.  <a href="#name-informative-references" class="xref">Informative References</a><a href="#section-toc.1-1.7.2.2.1" class="pilcrow">¶</a></p>
</li>
            </ul>
</li>
          <li class="ulEmpty toc compact" id="section-toc.1-1.8">
            <p id="section-toc.1-1.8.1"><a href="#section-appendix.a" class="xref"></a><a href="#name-acknowledgements" class="xref">Acknowledgements</a><a href="#section-toc.1-1.8.1" class="pilcrow">¶</a></p>
</li>
          <li class="ulEmpty toc compact" id="section-toc.1-1.9">
            <p id="section-toc.1-1.9.1"><a href="#section-appendix.b" class="xref"></a><a href="#name-authors-addresses" class="xref">Authors' Addresses</a><a href="#section-toc.1-1.9.1" class="pilcrow">¶</a></p>
</li>
        </ul>
</nav>
</section>
</div>
<div id="scope">
<section id="section-1">
      <h2 id="name-document-scope">
<a href="#section-1" class="section-number selfRef">1. </a><a href="#name-document-scope" class="section-name selfRef">Document Scope</a>
      </h2>
<p id="section-1-1">This document adds 'LoST-Validation' to the S-NAPTR Application
      Service Tag IANA registry and describes how this tag fits in the LoST
      server discovery procedure described in <span>[<a href="#RFC5222" class="xref">RFC5222</a>]</span>.  This tag is used with Naming Authority Pointer
      (NAPTR) Domain Name System (DNS) records so that clients of the
      Location-to-Service Translation (LoST) Protocol <span>[<a href="#RFC5222" class="xref">RFC5222</a>]</span> can identify servers designated for location validation.  This tag and the information on its use is an update to <span>[<a href="#RFC5222" class="xref">RFC5222</a>]</span> that enables the explicit discovery of a server that supports location validation.<a href="#section-1-1" class="pilcrow">¶</a></p>
</section>
</div>
<div id="intro">
<section id="section-2">
      <h2 id="name-introduction">
<a href="#section-2" class="section-number selfRef">2. </a><a href="#name-introduction" class="section-name selfRef">Introduction</a>
      </h2>
<p id="section-2-1">The LoST Protocol <span>[<a href="#RFC5222" class="xref">RFC5222</a>]</span> defines a mapping service with the
      additional ability for a client to request that a civic address be
      validated.  The LoST protocol allows servers to ignore a request to
      perform location validation.  The National Emergency Number Association
      (NENA) has defined an architecture for all-IP emergency services (known
      as "i3" <span>[<a href="#NENA-i3" class="xref">NENA-i3</a>]</span>), which defines the
      mapping (routing) and validation functions as two distinct functional
      elements, defined as an Emergency Call Routing Function (ECRF) and a
      Location Validation Function (LVF).  NENA i3 requires that the mapping
      (ECRF) and validation (LVF) functions be separable; an entity
      responsible for a LoST server cluster can decide to provide mapping and
      validation services using consolidated or separate server clusters
      (i.e., using the same or separate boxes).  The rationale is that the
      mapping service is used in real time during emergency call routing,
      while the validation service is used in advance, typically when data is
      provisioned; therefore, the mapping service has much higher availability
      and response-time requirements than the validation service.  An
      organization might choose to deploy these services using different
      server clusters to make it easier to provide higher levels of service
      for the mapping function while shielding it from the potentially bursty
      load of validation. Another organization might choose to use the same
      sets of servers for both services, configured and deployed to offer the high service level demanded of the mapping service.<a href="#section-2-1" class="pilcrow">¶</a></p>
<p id="section-2-2">In order to permit this separability, any entity querying a LoST
      server needs to be able to resolve an Application Unique String (AUS)
      into a URL for a LoST server designated for the required service (mapping
      or validation).  This separability needs to be maintained throughout the
      LoST tree structure, from forest guide to leaf node (LoST architecture
      is described in <span>[<a href="#RFC5582" class="xref">RFC5582</a>]</span>).  Because
      LoST referrals return an AUS rather than a URL, either a different
      service tag or a DNS name convention (e.g., "ecrf.example.org" and
      "lvf.example.org") is needed to differentiate between the services.  DNS name conventions are inflexible and fragile, making a different service tag the preferred approach.<a href="#section-2-2" class="pilcrow">¶</a></p>
<p id="section-2-3">Because LoST servers may ignore a request to perform location
      validation, a service tag explicitly for location validation also
      reduces the likelihood (which has existed since <span>[<a href="#RFC5582" class="xref">RFC5582</a>]</span>) that a client needing location validation will reach servers that are not doing so
      (due to configuration and/or conditions).<a href="#section-2-3" class="pilcrow">¶</a></p>
<div id="req">
<section id="section-2.1">
        <h3 id="name-requirements-language">
<a href="#section-2.1" class="section-number selfRef">2.1. </a><a href="#name-requirements-language" class="section-name selfRef">Requirements Language</a>
        </h3>
<p id="section-2.1-1">
    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-2.1-1" class="pilcrow">¶</a></p>
</section>
</div>
</section>
</div>
<div id="LoST-Validation">
<section id="section-3">
      <h2 id="name-the-lost-validation-applica">
<a href="#section-3" class="section-number selfRef">3. </a><a href="#name-the-lost-validation-applica" class="section-name selfRef">The LoST-Validation Application Service Tag</a>
      </h2>
<p id="section-3-1">This document adds 'LoST-Validation' to the "S-NAPTR Application
      Service Tags" registry created by <span>[<a href="#RFC3958" class="xref">RFC3958</a>]</span>.  The 'LoST-Validation' tag serves as a counterpart
      to the 'LoST' tag added by <span>[<a href="#RFC5222" class="xref">RFC5222</a>]</span>:
      the 'LoST' tag identifies servers able to perform the core mapping
      function, while 'LoST-Validation' identifies servers designated for the validation function.<a href="#section-3-1" class="pilcrow">¶</a></p>
<p id="section-3-2">Because some servers might be configured to provide both mapping and
      validation functions, a server identified using the 'LoST' service tag
      might also perform the validation function (and resolving the two tags
      might result in the same URL).  Because the two functions might be
      separate, clients seeking a LoST server for location validation can
      first try a URI-Enabled NAPTR (U-NAPTR) resolution using the
      'LoST-Validation' service tag and can fall back to the 'LoST' service tag if this does not resolve to a usable LoST server.<a href="#section-3-2" class="pilcrow">¶</a></p>
<p id="section-3-3">LoST <span>[<a href="#RFC5222" class="xref">RFC5222</a>]</span> specifies that LoST
      servers are located by resolving an AUS using U-NAPTR/DDDS (URI-Enabled
      NAPTR / Dynamic Delegation Discovery Service) <span>[<a href="#RFC4848" class="xref">RFC4848</a>]</span> and defines the 'LoST' application service tag.  In
      order to permit separability of the mapping and validation services
      performed using LoST, this document defines the 'LoST-Validation'
      service tag. This tag also reduces the likelihood that a client needing
      location validation might reach servers that are not performing validation (due to
      configuration and/or conditions).  NAPTR records for LoST servers available for location validation contain the 'LoST-Validation' service tag.  An entity needing to perform location validation using LoST performs the discovery procedure as described in <span>[<a href="#RFC5222" class="xref">RFC5222</a>]</span>, except that the 'LoST-Validation' service tag is used in preference to the 'LoST' service tag.  For both service tags, the HTTP and HTTPS URL schemes are used.  In the absence of any NAPTR records containing the 'LoST-Validation' service tag, the 'LoST' service tag is used.  Fallback to the 'LoST' service tag may follow if the 'LoST-Validation' service tag fails to result in a usable LoST server.  The discovery procedure with the 'LoST-Validation' service tag might result in the same URL as the 'LoST' service tag, or it may result in a different URL.  When the URLs are different, they could lead to the same physical servers or different servers.<a href="#section-3-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="back">
<section id="section-4">
      <h2 id="name-backwards-compatibility">
<a href="#section-4" class="section-number selfRef">4. </a><a href="#name-backwards-compatibility" class="section-name selfRef">Backwards Compatibility</a>
      </h2>
<p id="section-4-1">The primary use of LoST in general, and the location validation functionality in particular, is within the emergency services area.  Within North America, the NENA i3 <span>[<a href="#NENA-i3" class="xref">NENA-i3</a>]</span> document specifies how protocols including LoST are used.  The i3 document is expected to reference the 'LoST-Validation' service tag and specify its use in both server NAPTR DNS records and client resolution of AUS.<a href="#section-4-1" class="pilcrow">¶</a></p>
<p id="section-4-2">LoST allows a server to refuse to perform location validation and
      defines the 'locationValidationUnavailable' warning. LoST also allows a
      server to refer to another server rather than answering itself. So, in a
      deployment where a LoST tree has separate server clusters for mapping
      and for validation, mapping servers receiving a request for validation
      could either perform the validation as requested or return the
      'locationValidationUnavailable' warning and potentially also include a
      &lt;redirect&gt; element to redirect to a validation server. However,
      the &lt;redirect&gt; element contains an AUS, so
      unless the AUSs for validation and mapping are different (e.g.,
      'ecrf.example.org' and 'lvf.example.org'), we still need a different
      service tag to allow for flexible deployment choices (i.e., not
      requiring a DNS name convention).<a href="#section-4-2" class="pilcrow">¶</a></p>
<p id="section-4-3">LoST clients performing emergency services operations in North
      America are expected to
      comply with the NENA i3 specification and hence support the
      'LoST-Validation' service tag when defined.  A LoST client implemented
      prior to the addition of the 'LoST-Validation' tag would use the 'LoST'
      tag to resolve an AUS.  Such a client might not be performing location
      validation, but if it is, the LoST server it contacts may perform the
      service.  Even in a deployment where mapping and validation are split,
      the data is identical; the split is a load and deployment optimization
      strategy.  Servers designated for mapping might perform validation when
      requested (potentially depending on load or other factors).  If an older
      client attempts validation using a designated mapping server that
      refuses the request, the client will retry later, at which point the
      server might provide the function (e.g., if its load or other conditions
      have changed).  Even
      in the case of a designated mapping server that refuses to
      perform validation at any time, the server could return a redirect with
      a different AUS (e.g., "lvf.example.com") that resolves to a designated
      validation server.  In the worst case, the client will be
      unable to reach a server willing to perform validation and will follow
      up (e.g., submit a discrepancy report as specified in NENA i3).  The
      resolution may be to update the client with the 'LoST-Validation'
      service tag, update the AUS returned in a redirect and DNS to use a
      different DNS host name, or permit the server to perform validation when
      not under stress (or a combination).  Note that, because LoST does not
      require servers to perform validation, the situation described can exist
      regardless of the addition of the 'LoST-Validation' service tag.  Use of
      the tag improves the likelihood that a client is able to validate a
      location when needed.<a href="#section-4-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="security">
<section id="section-5">
      <h2 id="name-security-considerations">
<a href="#section-5" class="section-number selfRef">5. </a><a href="#name-security-considerations" class="section-name selfRef">Security Considerations</a>
      </h2>
<p id="section-5-1">The security considerations described in <span>[<a href="#RFC3958" class="xref">RFC3958</a>]</span>, <span>[<a href="#RFC4848" class="xref">RFC4848</a>]</span>, and <span>[<a href="#RFC5222" class="xref">RFC5222</a>]</span> apply here.  No additional security
      aspects are foreseen by the addition of an extra tag.  Separation of
      services might be desired, for example, to be able to allocate different levels of resources (such as server capacity, attack mitigation, bandwidth, etc.) to the mapping and validation services, in which case separate tags are needed to allow LoST clients (which may include other LoST servers) to identify the correct server cluster.<a href="#section-5-1" class="pilcrow">¶</a></p>
<p id="section-5-2"><span>[<a href="#RFC5222" class="xref">RFC5222</a>]</span> descriptively discusses the
      use of DNS security <span>[<a href="#RFC4033" class="xref">RFC4033</a>]</span> to
      mitigate the risk of DNS-based attacks.  Because DNS security has become
      more widely deployed since the publication of <span>[<a href="#RFC5222" class="xref">RFC5222</a>]</span>, such measures <span class="bcp14">SHOULD</span> be used when
      performing NAPTR resolution.  Note that, while there are valid reasons
      to proceed with a LoST mapping query despite security failures while
      initiating or processing an emergency call, these concerns generally do
      not apply to a LoST validation query done in advance of an emergency
      call.<a href="#section-5-2" class="pilcrow">¶</a></p>
</section>
</div>
<div id="iana">
<section id="section-6">
      <h2 id="name-iana-considerations">
<a href="#section-6" class="section-number selfRef">6. </a><a href="#name-iana-considerations" class="section-name selfRef">IANA Considerations</a>
      </h2>
<p id="section-6-1">IANA has added 'LoST-Validation' to the "S-NAPTR Application Service
      Tags" registry created by <span>[<a href="#RFC3958" class="xref">RFC3958</a>]</span>.
      This tag serves as a counterpart to the 'LoST' tag added by <span>[<a href="#RFC5222" class="xref">RFC5222</a>]</span>.<a href="#section-6-1" class="pilcrow">¶</a></p>
<p id="section-6-2">(Note that IANA and <span>[<a href="#RFC3958" class="xref">RFC3958</a>]</span> call this registry "S-NAPTR Application Service Tags", while <span>[<a href="#RFC5222" class="xref">RFC5222</a>]</span> calls it "U-NAPTR application service tag".)<a href="#section-6-2" class="pilcrow">¶</a></p>
<section id="section-6.1">
        <h3 id="name-s-naptr-registration">
<a href="#section-6.1" class="section-number selfRef">6.1. </a><a href="#name-s-naptr-registration" class="section-name selfRef">S-NAPTR Registration</a>
        </h3>
<p id="section-6.1-1">This document registers an S-NAPTR application service tag:<a href="#section-6.1-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-6.1-2">
          <dt id="section-6.1-2.1">Application Service Tag:</dt>
          <dd style="margin-left: 1.5em" id="section-6.1-2.2">LoST-Validation<a href="#section-6.1-2.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-6.1-2.3">Defining Publication:</dt>
          <dd style="margin-left: 1.5em" id="section-6.1-2.4">This document<a href="#section-6.1-2.4" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
</section>
</section>
</div>
<section id="section-7">
      <h2 id="name-references">
<a href="#section-7" class="section-number selfRef">7. </a><a href="#name-references" class="section-name selfRef">References</a>
      </h2>
<section id="section-7.1">
        <h3 id="name-normative-references">
<a href="#section-7.1" class="section-number selfRef">7.1. </a><a href="#name-normative-references" class="section-name selfRef">Normative References</a>
        </h3>
<dl class="references">
<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="RFC3958">[RFC3958]</dt>
        <dd>
<span class="refAuthor">Daigle, L.</span><span class="refAuthor"> and A. Newton</span>, <span class="refTitle">"Domain-Based Application Service Location Using SRV RRs and the Dynamic Delegation Discovery Service (DDDS)"</span>, <span class="seriesInfo">RFC 3958</span>, <span class="seriesInfo">DOI 10.17487/RFC3958</span>, <time datetime="2005-01" class="refDate">January 2005</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc3958">https://www.rfc-editor.org/info/rfc3958</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC4033">[RFC4033]</dt>
        <dd>
<span class="refAuthor">Arends, R.</span><span class="refAuthor">, Austein, R.</span><span class="refAuthor">, Larson, M.</span><span class="refAuthor">, Massey, D.</span><span class="refAuthor">, and S. Rose</span>, <span class="refTitle">"DNS Security Introduction and Requirements"</span>, <span class="seriesInfo">RFC 4033</span>, <span class="seriesInfo">DOI 10.17487/RFC4033</span>, <time datetime="2005-03" class="refDate">March 2005</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4033">https://www.rfc-editor.org/info/rfc4033</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC4848">[RFC4848]</dt>
        <dd>
<span class="refAuthor">Daigle, L.</span>, <span class="refTitle">"Domain-Based Application Service Location Using URIs and the Dynamic Delegation Discovery Service (DDDS)"</span>, <span class="seriesInfo">RFC 4848</span>, <span class="seriesInfo">DOI 10.17487/RFC4848</span>, <time datetime="2007-04" class="refDate">April 2007</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4848">https://www.rfc-editor.org/info/rfc4848</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC5222">[RFC5222]</dt>
        <dd>
<span class="refAuthor">Hardie, T.</span><span class="refAuthor">, Newton, A.</span><span class="refAuthor">, Schulzrinne, H.</span><span class="refAuthor">, and H. Tschofenig</span>, <span class="refTitle">"LoST: A Location-to-Service Translation Protocol"</span>, <span class="seriesInfo">RFC 5222</span>, <span class="seriesInfo">DOI 10.17487/RFC5222</span>, <time datetime="2008-08" class="refDate">August 2008</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc5222">https://www.rfc-editor.org/info/rfc5222</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>
</dl>
</section>
<section id="section-7.2">
        <h3 id="name-informative-references">
<a href="#section-7.2" class="section-number selfRef">7.2. </a><a href="#name-informative-references" class="section-name selfRef">Informative References</a>
        </h3>
<dl class="references">
<dt id="NENA-i3">[NENA-i3]</dt>
        <dd>
<span class="refAuthor">National Emergency Number Association (NENA) Interconnection and Security Committee, i3 Architecture Working Group</span>, <span class="refTitle">"Detailed Functional and Interface Standards for the NENA i3 Solution"</span>, <time datetime="2016" class="refDate">2016</time>, <span>&lt;<a href="https://www.nena.org/page/i3_Stage3">https://www.nena.org/page/i3_Stage3</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC5582">[RFC5582]</dt>
      <dd>
<span class="refAuthor">Schulzrinne, H.</span>, <span class="refTitle">"Location-to-URL Mapping Architecture and Framework"</span>, <span class="seriesInfo">RFC 5582</span>, <span class="seriesInfo">DOI 10.17487/RFC5582</span>, <time datetime="2009-09" class="refDate">September 2009</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc5582">https://www.rfc-editor.org/info/rfc5582</a>&gt;</span>. </dd>
<dd class="break"></dd>
</dl>
</section>
</section>
<section id="section-appendix.a">
      <h2 id="name-acknowledgements">
<a href="#name-acknowledgements" class="section-name selfRef">Acknowledgements</a>
      </h2>
<p id="section-appendix.a-1">Many thanks to <span class="contact-name">Ted Hardie</span>, <span class="contact-name">Ben Campbell</span>, <span class="contact-name">Dan Banks</span>, <span class="contact-name">Pete Resnick</span>, <span class="contact-name">Shawn Emery</span>, <span class="contact-name">Robert Wilton</span>, <span class="contact-name">Roman Danyliw</span>, and <span class="contact-name">Benjamin Kaduk</span> for their helpful reviews and suggestions and to <span class="contact-name">Barry Leiba</span> for shepherding the document.<a href="#section-appendix.a-1" class="pilcrow">¶</a></p>
</section>
<div id="authors-addresses">
<section id="section-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">Randall Gellens</span></div>
<div dir="auto" class="left"><span class="org">Core Technology Consulting</span></div>
<div dir="auto" class="left"><span class="country-name">United States of America</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:rg+ietf@coretechnologyconsulting.com" class="email">rg+ietf@coretechnologyconsulting.com</a>
</div>
<div class="url">
<span>URI:</span>
<a href="http://www.coretechnologyconsulting.com" class="url">http://www.coretechnologyconsulting.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Brian Rosen</span></div>
<div dir="auto" class="left"><span class="street-address">470 Conrad Dr.</span></div>
<div dir="auto" class="left">
<span class="locality">Mars</span>, <span class="region">PA</span> <span class="postal-code">16046</span>
</div>
<div dir="auto" class="left"><span class="country-name">United States of America</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:br@brianrosen.net" class="email">br@brianrosen.net</a>
</div>
</address>
</section>
</div>
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