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<pre>Request for Comments: 698 Jul 1975
NIC #32964
<span class="h1">TELNET EXTENDED ASCII OPTION</span>
<span class="h2"><a class="selflink" id="section-1" href="#section-1">1</a>. Command Name and Code.</span>
EXTEND-ASCII 17
<span class="h2"><a class="selflink" id="section-2" href="#section-2">2</a>. Command Meanings.</span>
IAC WILL EXTEND-ASCII
The sender of this command requests Permission to begin
transmitting, or confirms that it may now begin transmitting
extended ASCII, where additional 'control' bits are added to
normal ASCII, which are treated sPecially by certain programs on
the host computer.
IAC WON'T EXTEND-ASCII
If the connection is already being operated in extended ASCII
mode, the sender of this command demands that the receiver begin
transmitting data characters in standard NVT ASCII. If the
connection is not already being operated in extended ASCII mode,
The sender of this command refuses to begin transmitting extended
ASCII.
IAC DO EXTEND-ASCII
The sender of this command requests that the receiver begin
transmitting,or confirms that the receiver of this command is
allowed to begin transmitting extended ASCII.
IAC DON'T EXTEND-ASCII
The sender of this command demands that the receiver of this
command stop or not start transmitting data in extended ASCII
mode.
IAC SB EXTASC
<high order bits (bits 15-8)><low order bits (bits 7-0)> IAC SE
This command transmits an extended ASCII character in the form of
two 8-bit bytes. Each 8-bit byte contains 8 data bits.
-1-</pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'>TELNET EXTENDED ASCII OPTION
<a href="./rfc698">RFC 698</a>, NIC 32964 (July 23 1975)
<span class="h2"><a class="selflink" id="section-3" href="#section-3">3</a>. Default</span>
DON'T EXTEND-ASCII
WON'T EXTEND-ASCII
i.e., only use standard NVT ASCII
<span class="h2"><a class="selflink" id="section-4" href="#section-4">4</a>. Motivation.</span>
Several sites on the net, for example, SU-AI and MIT-AI, use
keyboards which use almost all 128 characters as printable
characters, and use one or more additional bits as "control' bits as
command modifiers or to separate textual input from command input to
programs. Without these additional bits, several characters cannot
be entered as text because they are used for control purposes, such
as the greek letter "beta' which on a TELNET connection is CONTROL-C
and is used for stopping ones job. In addition there are several
commonly used programs at these sites which require these additional
bits to be run effectively. Hence it is necessary to provide some
means of sending characters larger than 8 bits wide.
<span class="h2"><a class="selflink" id="section-5" href="#section-5">5</a>. Description of the option.</span>
This option is to allow the transmission of extended ASCII.
Experience has shown that most of the time, 7-bit ASCII is typed,
with an occasional "control' character used. Hence, it is expected
normal NVT ASCII would be used for 7-bit ASCII and that
extended-ASCII be sent as an escape character sequence.
The exact meaning of these additional bits depends on the user
program. At SU-AI and at MIT-AI, the first two bits beyond the
normal 7-bit ASCII are passed on to the user program and are denoted
as follows.
Bit 8 (or 200 octal) is the CONTROL bit
Bit 9 (or 400 octal) is the META bit
(NOTE: "CONTROL' is used in a non-standard way here; that is, it
usually refers to codes 0-37 in NVT ASCII. CONTROL and META are
echoed by prefixing the normal character with 013 (integral symbol)
for CONTROL and 014 (plus-minus) for META. If both are present, it
is known as CONTROL-META and echoed as 013 014 7-bit character.)
-2-</pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'>TELNET EXTENDED ASCII OPTION
<a href="./rfc698">RFC 698</a>, NIC 32964 (July 23, 1975)
<span class="h2"><a class="selflink" id="section-6" href="#section-6">6</a>. Description of Stanford Extended ASCII Characters</span>
In this section, the extended graphic character set used at SU-AI is
described for reference, although this specific character set is not
required as part of the extended ASCII Telnet option. Characters
described as "hidden" are alternate graphic interpretations of codes
normally used as format effectors, used by certain typesetting
programs.
Code Graphic represented
<span class="h2"><a class="selflink" id="section-000" href="#section-000">000</a> null (hidden vertically centered dot)</span>
<span class="h2"><a class="selflink" id="section-001" href="#section-001">001</a> downward arrow</span>
<span class="h2"><a class="selflink" id="section-002" href="#section-002">002</a> alpha (all Greek letters are lowercase)</span>
<span class="h2"><a class="selflink" id="section-003" href="#section-003">003</a> beta</span>
<span class="h2"><a class="selflink" id="section-004" href="#section-004">004</a> logical and (caret)</span>
<span class="h2"><a class="selflink" id="section-005" href="#section-005">005</a> logical not (dash with downward extension)</span>
<span class="h2"><a class="selflink" id="section-006" href="#section-006">006</a> epsilon</span>
<span class="h2"><a class="selflink" id="section-007" href="#section-007">007</a> pi</span>
<span class="h2"><a class="selflink" id="section-010" href="#section-010">010</a> lambda</span>
<span class="h2"><a class="selflink" id="section-011" href="#section-011">011</a> tab (hidden gamma)</span>
<span class="h2"><a class="selflink" id="section-012" href="#section-012">012</a> linefeed (hidden delta)</span>
<span class="h2"><a class="selflink" id="section-013" href="#section-013">013</a> vertical tab (hidden integral)</span>
<span class="h2"><a class="selflink" id="section-014" href="#section-014">014</a> formfeed (hidden plus-minus)</span>
<span class="h2"><a class="selflink" id="section-015" href="#section-015">015</a> carriage return (hidden circled-plus)</span>
<span class="h2"><a class="selflink" id="section-016" href="#section-016">016</a> infinity</span>
<span class="h2"><a class="selflink" id="section-017" href="#section-017">017</a> del (partial differential)</span>
<span class="h2"><a class="selflink" id="section-020" href="#section-020">020</a> proper subset (right-opening horseshoe)</span>
<span class="h2"><a class="selflink" id="section-021" href="#section-021">021</a> proper superset (left-opening horseshoe)</span>
<span class="h2"><a class="selflink" id="section-022" href="#section-022">022</a> intersection (down-opening horseshoe)</span>
<span class="h2"><a class="selflink" id="section-023" href="#section-023">023</a> union (up-opening horseshoe)</span>
<span class="h2"><a class="selflink" id="section-024" href="#section-024">024</a> universal quantifier (upside-down A)</span>
<span class="h2"><a class="selflink" id="section-025" href="#section-025">025</a> existential quantifier (backwards E)</span>
<span class="h2"><a class="selflink" id="section-026" href="#section-026">026</a> circled-times</span>
<span class="h2"><a class="selflink" id="section-027" href="#section-027">027</a> left-right double headed arrow</span>
<span class="h2"><a class="selflink" id="section-030" href="#section-030">030</a> underbar</span>
<span class="h2"><a class="selflink" id="section-031" href="#section-031">031</a> right pointing arrow</span>
<span class="h2"><a class="selflink" id="section-032" href="#section-032">032</a> tilde</span>
<span class="h2"><a class="selflink" id="section-033" href="#section-033">033</a> not-equal</span>
<span class="h2"><a class="selflink" id="section-034" href="#section-034">034</a> less-than-or-equal</span>
<span class="h2"><a class="selflink" id="section-035" href="#section-035">035</a> greater-than-or-equal</span>
<span class="h2"><a class="selflink" id="section-036" href="#section-036">036</a> equivalence (column of 3 horizontal bars)</span>
<span class="h2"><a class="selflink" id="section-037" href="#section-037">037</a> logical or (V shape)</span>
040-135 as in standard ASCII
-3-</pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'>TELNET EXTENDED ASCII OPTION
<a href="./rfc698">RFC 698</a>, NIC 32964 (July 23, 1975)
<span class="h2"><a class="selflink" id="section-136" href="#section-136">136</a> upward pointing arrow</span>
<span class="h2"><a class="selflink" id="section-137" href="#section-137">137</a> left pointing arrow</span>
140-174 as in standard ASCII
<span class="h2"><a class="selflink" id="section-175" href="#section-175">175</a> altmode (prints as lozenge)</span>
<span class="h2"><a class="selflink" id="section-176" href="#section-176">176</a> right brace</span>
<span class="h2"><a class="selflink" id="section-177" href="#section-177">177</a> rubout (hidden circumflex)</span>
-4-
</pre>
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