technical/protocol-capabilities.html - external/gitster/git-htmldocs - Git at Google

 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
  "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
 <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
 <head>
 <meta http-equiv="Content-Type" content="application/xhtml+xml; charset=UTF-8" />
 <meta name="generator" content="AsciiDoc 8.6.8" />
 <title>Git Protocol Capabilities</title>
 <style type="text/css">
 /* Shared CSS for AsciiDoc xhtml11 and html5 backends */

 /* Default font. */
 body {
  font-family: Georgia,serif;
 }

 /* Title font. */
 h1, h2, h3, h4, h5, h6,
 div.title, caption.title,
 thead, p.table.header,
 #toctitle,
 #author, #revnumber, #revdate, #revremark,
 #footer {
  font-family: Arial,Helvetica,sans-serif;
 }

 body {
  margin: 1em 5% 1em 5%;
 }

 a {
  color: blue;
  text-decoration: underline;
 }
 a:visited {
  color: fuchsia;
 }

 em {
  font-style: italic;
  color: navy;
 }

 strong {
  font-weight: bold;
  color: #083194;
 }

 h1, h2, h3, h4, h5, h6 {
  color: #527bbd;
  margin-top: 1.2em;
  margin-bottom: 0.5em;
  line-height: 1.3;
 }

 h1, h2, h3 {
  border-bottom: 2px solid silver;
 }
 h2 {
  padding-top: 0.5em;
 }
 h3 {
  float: left;
 }
 h3 + * {
  clear: left;
 }
 h5 {
  font-size: 1.0em;
 }

 div.sectionbody {
  margin-left: 0;
 }

 hr {
  border: 1px solid silver;
 }

 p {
  margin-top: 0.5em;
  margin-bottom: 0.5em;
 }

 ul, ol, li > p {
  margin-top: 0;
 }
 ul > li { color: #aaa; }
 ul > li > * { color: black; }

 .monospaced, code, pre {
  font-family: "Courier New", Courier, monospace;
  font-size: inherit;
  color: navy;
  padding: 0;
  margin: 0;
 }


 #author {
  color: #527bbd;
  font-weight: bold;
  font-size: 1.1em;
 }
 #email {
 }
 #revnumber, #revdate, #revremark {
 }

 #footer {
  font-size: small;
  border-top: 2px solid silver;
  padding-top: 0.5em;
  margin-top: 4.0em;
 }
 #footer-text {
  float: left;
  padding-bottom: 0.5em;
 }
 #footer-badges {
  float: right;
  padding-bottom: 0.5em;
 }

 #preamble {
  margin-top: 1.5em;
  margin-bottom: 1.5em;
 }
 div.imageblock, div.exampleblock, div.verseblock,
 div.quoteblock, div.literalblock, div.listingblock, div.sidebarblock,
 div.admonitionblock {
  margin-top: 1.0em;
  margin-bottom: 1.5em;
 }
 div.admonitionblock {
  margin-top: 2.0em;
  margin-bottom: 2.0em;
  margin-right: 10%;
  color: #606060;
 }

 div.content { /* Block element content. */
  padding: 0;
 }

 /* Block element titles. */
 div.title, caption.title {
  color: #527bbd;
  font-weight: bold;
  text-align: left;
  margin-top: 1.0em;
  margin-bottom: 0.5em;
 }
 div.title + * {
  margin-top: 0;
 }

 td div.title:first-child {
  margin-top: 0.0em;
 }
 div.content div.title:first-child {
  margin-top: 0.0em;
 }
 div.content + div.title {
  margin-top: 0.0em;
 }

 div.sidebarblock > div.content {
  background: #ffffee;
  border: 1px solid #dddddd;
  border-left: 4px solid #f0f0f0;
  padding: 0.5em;
 }

 div.listingblock > div.content {
  border: 1px solid #dddddd;
  border-left: 5px solid #f0f0f0;
  background: #f8f8f8;
  padding: 0.5em;
 }

 div.quoteblock, div.verseblock {
  padding-left: 1.0em;
  margin-left: 1.0em;
  margin-right: 10%;
  border-left: 5px solid #f0f0f0;
  color: #888;
 }

 div.quoteblock > div.attribution {
  padding-top: 0.5em;
  text-align: right;
 }

 div.verseblock > pre.content {
  font-family: inherit;
  font-size: inherit;
 }
 div.verseblock > div.attribution {
  padding-top: 0.75em;
  text-align: left;
 }
 /* DEPRECATED: Pre version 8.2.7 verse style literal block. */
 div.verseblock + div.attribution {
  text-align: left;
 }

 div.admonitionblock .icon {
  vertical-align: top;
  font-size: 1.1em;
  font-weight: bold;
  text-decoration: underline;
  color: #527bbd;
  padding-right: 0.5em;
 }
 div.admonitionblock td.content {
  padding-left: 0.5em;
  border-left: 3px solid #dddddd;
 }

 div.exampleblock > div.content {
  border-left: 3px solid #dddddd;
  padding-left: 0.5em;
 }

 div.imageblock div.content { padding-left: 0; }
 span.image img { border-style: none; }
 a.image:visited { color: white; }

 dl {
  margin-top: 0.8em;
  margin-bottom: 0.8em;
 }
 dt {
  margin-top: 0.5em;
  margin-bottom: 0;
  font-style: normal;
  color: navy;
 }
 dd > *:first-child {
  margin-top: 0.1em;
 }

 ul, ol {
  list-style-position: outside;
 }
 ol.arabic {
  list-style-type: decimal;
 }
 ol.loweralpha {
  list-style-type: lower-alpha;
 }
 ol.upperalpha {
  list-style-type: upper-alpha;
 }
 ol.lowerroman {
  list-style-type: lower-roman;
 }
 ol.upperroman {
  list-style-type: upper-roman;
 }

 div.compact ul, div.compact ol,
 div.compact p, div.compact p,
 div.compact div, div.compact div {
  margin-top: 0.1em;
  margin-bottom: 0.1em;
 }

 tfoot {
  font-weight: bold;
 }
 td > div.verse {
  white-space: pre;
 }

 div.hdlist {
  margin-top: 0.8em;
  margin-bottom: 0.8em;
 }
 div.hdlist tr {
  padding-bottom: 15px;
 }
 dt.hdlist1.strong, td.hdlist1.strong {
  font-weight: bold;
 }
 td.hdlist1 {
  vertical-align: top;
  font-style: normal;
  padding-right: 0.8em;
  color: navy;
 }
 td.hdlist2 {
  vertical-align: top;
 }
 div.hdlist.compact tr {
  margin: 0;
  padding-bottom: 0;
 }

 .comment {
  background: yellow;
 }

 .footnote, .footnoteref {
  font-size: 0.8em;
 }

 span.footnote, span.footnoteref {
  vertical-align: super;
 }

 #footnotes {
  margin: 20px 0 20px 0;
  padding: 7px 0 0 0;
 }

 #footnotes div.footnote {
  margin: 0 0 5px 0;
 }

 #footnotes hr {
  border: none;
  border-top: 1px solid silver;
  height: 1px;
  text-align: left;
  margin-left: 0;
  width: 20%;
  min-width: 100px;
 }

 div.colist td {
  padding-right: 0.5em;
  padding-bottom: 0.3em;
  vertical-align: top;
 }
 div.colist td img {
  margin-top: 0.3em;
 }

 @media print {
  #footer-badges { display: none; }
 }

 #toc {
  margin-bottom: 2.5em;
 }

 #toctitle {
  color: #527bbd;
  font-size: 1.1em;
  font-weight: bold;
  margin-top: 1.0em;
  margin-bottom: 0.1em;
 }

 div.toclevel0, div.toclevel1, div.toclevel2, div.toclevel3, div.toclevel4 {
  margin-top: 0;
  margin-bottom: 0;
 }
 div.toclevel2 {
  margin-left: 2em;
  font-size: 0.9em;
 }
 div.toclevel3 {
  margin-left: 4em;
  font-size: 0.9em;
 }
 div.toclevel4 {
  margin-left: 6em;
  font-size: 0.9em;
 }

 span.aqua { color: aqua; }
 span.black { color: black; }
 span.blue { color: blue; }
 span.fuchsia { color: fuchsia; }
 span.gray { color: gray; }
 span.green { color: green; }
 span.lime { color: lime; }
 span.maroon { color: maroon; }
 span.navy { color: navy; }
 span.olive { color: olive; }
 span.purple { color: purple; }
 span.red { color: red; }
 span.silver { color: silver; }
 span.teal { color: teal; }
 span.white { color: white; }
 span.yellow { color: yellow; }

 span.aqua-background { background: aqua; }
 span.black-background { background: black; }
 span.blue-background { background: blue; }
 span.fuchsia-background { background: fuchsia; }
 span.gray-background { background: gray; }
 span.green-background { background: green; }
 span.lime-background { background: lime; }
 span.maroon-background { background: maroon; }
 span.navy-background { background: navy; }
 span.olive-background { background: olive; }
 span.purple-background { background: purple; }
 span.red-background { background: red; }
 span.silver-background { background: silver; }
 span.teal-background { background: teal; }
 span.white-background { background: white; }
 span.yellow-background { background: yellow; }

 span.big { font-size: 2em; }
 span.small { font-size: 0.6em; }

 span.underline { text-decoration: underline; }
 span.overline { text-decoration: overline; }
 span.line-through { text-decoration: line-through; }

 div.unbreakable { page-break-inside: avoid; }


 /*
  * xhtml11 specific
  *
  * */

 div.tableblock {
  margin-top: 1.0em;
  margin-bottom: 1.5em;
 }
 div.tableblock > table {
  border: 3px solid #527bbd;
 }
 thead, p.table.header {
  font-weight: bold;
  color: #527bbd;
 }
 p.table {
  margin-top: 0;
 }
 /* Because the table frame attribute is overriden by CSS in most browsers. */
 div.tableblock > table[frame="void"] {
  border-style: none;
 }
 div.tableblock > table[frame="hsides"] {
  border-left-style: none;
  border-right-style: none;
 }
 div.tableblock > table[frame="vsides"] {
  border-top-style: none;
  border-bottom-style: none;
 }


 /*
  * html5 specific
  *
  * */

 table.tableblock {
  margin-top: 1.0em;
  margin-bottom: 1.5em;
 }
 thead, p.tableblock.header {
  font-weight: bold;
  color: #527bbd;
 }
 p.tableblock {
  margin-top: 0;
 }
 table.tableblock {
  border-width: 3px;
  border-spacing: 0px;
  border-style: solid;
  border-color: #527bbd;
  border-collapse: collapse;
 }
 th.tableblock, td.tableblock {
  border-width: 1px;
  padding: 4px;
  border-style: solid;
  border-color: #527bbd;
 }

 table.tableblock.frame-topbot {
  border-left-style: hidden;
  border-right-style: hidden;
 }
 table.tableblock.frame-sides {
  border-top-style: hidden;
  border-bottom-style: hidden;
 }
 table.tableblock.frame-none {
  border-style: hidden;
 }

 th.tableblock.halign-left, td.tableblock.halign-left {
  text-align: left;
 }
 th.tableblock.halign-center, td.tableblock.halign-center {
  text-align: center;
 }
 th.tableblock.halign-right, td.tableblock.halign-right {
  text-align: right;
 }

 th.tableblock.valign-top, td.tableblock.valign-top {
  vertical-align: top;
 }
 th.tableblock.valign-middle, td.tableblock.valign-middle {
  vertical-align: middle;
 }
 th.tableblock.valign-bottom, td.tableblock.valign-bottom {
  vertical-align: bottom;
 }


 /*
  * manpage specific
  *
  * */

 body.manpage h1 {
  padding-top: 0.5em;
  padding-bottom: 0.5em;
  border-top: 2px solid silver;
  border-bottom: 2px solid silver;
 }
 body.manpage h2 {
  border-style: none;
 }
 body.manpage div.sectionbody {
  margin-left: 3em;
 }

 @media print {
  body.manpage div#toc { display: none; }
 }


 </style>
 <script type="text/javascript">
 /*<![CDATA[*/
 var asciidoc = { // Namespace.

 /////////////////////////////////////////////////////////////////////
 // Table Of Contents generator
 /////////////////////////////////////////////////////////////////////

 /* Author: Mihai Bazon, September 2002
  * http://students.infoiasi.ro/~mishoo
  *
  * Table Of Content generator
  * Version: 0.4
  *
  * Feel free to use this script under the terms of the GNU General Public
  * License, as long as you do not remove or alter this notice.
  */

  /* modified by Troy D. Hanson, September 2006. License: GPL */
  /* modified by Stuart Rackham, 2006, 2009. License: GPL */

 // toclevels = 1..4.
 toc: function (toclevels) {

  function getText(el) {
  var text = "";
  for (var i = el.firstChild; i != null; i = i.nextSibling) {
  if (i.nodeType == 3 /* Node.TEXT_NODE */) // IE doesn't speak constants.
  text += i.data;
  else if (i.firstChild != null)
  text += getText(i);
  }
  return text;
  }

  function TocEntry(el, text, toclevel) {
  this.element = el;
  this.text = text;
  this.toclevel = toclevel;
  }

  function tocEntries(el, toclevels) {
  var result = new Array;
  var re = new RegExp('[hH]([1-'+(toclevels+1)+'])');
  // Function that scans the DOM tree for header elements (the DOM2
  // nodeIterator API would be a better technique but not supported by all
  // browsers).
  var iterate = function (el) {
  for (var i = el.firstChild; i != null; i = i.nextSibling) {
  if (i.nodeType == 1 /* Node.ELEMENT_NODE */) {
  var mo = re.exec(i.tagName);
  if (mo && (i.getAttribute("class") || i.getAttribute("className")) != "float") {
  result[result.length] = new TocEntry(i, getText(i), mo[1]-1);
  }
  iterate(i);
  }
  }
  }
  iterate(el);
  return result;
  }

  var toc = document.getElementById("toc");
  if (!toc) {
  return;
  }

  // Delete existing TOC entries in case we're reloading the TOC.
  var tocEntriesToRemove = [];
  var i;
  for (i = 0; i < toc.childNodes.length; i++) {
  var entry = toc.childNodes[i];
  if (entry.nodeName.toLowerCase() == 'div'
  && entry.getAttribute("class")
  && entry.getAttribute("class").match(/^toclevel/))
  tocEntriesToRemove.push(entry);
  }
  for (i = 0; i < tocEntriesToRemove.length; i++) {
  toc.removeChild(tocEntriesToRemove[i]);
  }

  // Rebuild TOC entries.
  var entries = tocEntries(document.getElementById("content"), toclevels);
  for (var i = 0; i < entries.length; ++i) {
  var entry = entries[i];
  if (entry.element.id == "")
  entry.element.id = "_toc_" + i;
  var a = document.createElement("a");
  a.href = "#" + entry.element.id;
  a.appendChild(document.createTextNode(entry.text));
  var div = document.createElement("div");
  div.appendChild(a);
  div.className = "toclevel" + entry.toclevel;
  toc.appendChild(div);
  }
  if (entries.length == 0)
  toc.parentNode.removeChild(toc);
 },


 /////////////////////////////////////////////////////////////////////
 // Footnotes generator
 /////////////////////////////////////////////////////////////////////

 /* Based on footnote generation code from:
  * http://www.brandspankingnew.net/archive/2005/07/format_footnote.html
  */

 footnotes: function () {
  // Delete existing footnote entries in case we're reloading the footnodes.
  var i;
  var noteholder = document.getElementById("footnotes");
  if (!noteholder) {
  return;
  }
  var entriesToRemove = [];
  for (i = 0; i < noteholder.childNodes.length; i++) {
  var entry = noteholder.childNodes[i];
  if (entry.nodeName.toLowerCase() == 'div' && entry.getAttribute("class") == "footnote")
  entriesToRemove.push(entry);
  }
  for (i = 0; i < entriesToRemove.length; i++) {
  noteholder.removeChild(entriesToRemove[i]);
  }

  // Rebuild footnote entries.
  var cont = document.getElementById("content");
  var spans = cont.getElementsByTagName("span");
  var refs = {};
  var n = 0;
  for (i=0; i<spans.length; i++) {
  if (spans[i].className == "footnote") {
  n++;
  var note = spans[i].getAttribute("data-note");
  if (!note) {
  // Use [\s\S] in place of . so multi-line matches work.
  // Because JavaScript has no s (dotall) regex flag.
  note = spans[i].innerHTML.match(/\s*\[([\s\S]*)]\s*/)[1];
  spans[i].innerHTML =
  "[<a id='_footnoteref_" + n + "' href='#_footnote_" + n +
  "' title='View footnote' class='footnote'>" + n + "</a>]";
  spans[i].setAttribute("data-note", note);
  }
  noteholder.innerHTML +=
  "<div class='footnote' id='_footnote_" + n + "'>" +
  "<a href='#_footnoteref_" + n + "' title='Return to text'>" +
  n + "</a>. " + note + "</div>";
  var id =spans[i].getAttribute("id");
  if (id != null) refs["#"+id] = n;
  }
  }
  if (n == 0)
  noteholder.parentNode.removeChild(noteholder);
  else {
  // Process footnoterefs.
  for (i=0; i<spans.length; i++) {
  if (spans[i].className == "footnoteref") {
  var href = spans[i].getElementsByTagName("a")[0].getAttribute("href");
  href = href.match(/#.*/)[0]; // Because IE return full URL.
  n = refs[href];
  spans[i].innerHTML =
  "[<a href='#_footnote_" + n +
  "' title='View footnote' class='footnote'>" + n + "</a>]";
  }
  }
  }
 },

 install: function(toclevels) {
  var timerId;

  function reinstall() {
  asciidoc.footnotes();
  if (toclevels) {
  asciidoc.toc(toclevels);
  }
  }

  function reinstallAndRemoveTimer() {
  clearInterval(timerId);
  reinstall();
  }

  timerId = setInterval(reinstall, 500);
  if (document.addEventListener)
  document.addEventListener("DOMContentLoaded", reinstallAndRemoveTimer, false);
  else
  window.onload = reinstallAndRemoveTimer;
 }

 }
 asciidoc.install();
 /*]]>*/
 </script>
 </head>
 <body class="article">
 <div id="header">
 <h1>Git Protocol Capabilities</h1>
 </div>
 <div id="content">
 <div id="preamble">
 <div class="sectionbody">
 <div class="paragraph"><p>Servers SHOULD support all capabilities defined in this document.</p></div>
 <div class="paragraph"><p>On the very first line of the initial server response of either
 receive-pack and upload-pack the first reference is followed by
 a NUL byte and then a list of space delimited server capabilities.
 These allow the server to declare what it can and cannot support
 to the client.</p></div>
 <div class="paragraph"><p>Client will then send a space separated list of capabilities it wants
 to be in effect. The client MUST NOT ask for capabilities the server
 did not say it supports.</p></div>
 <div class="paragraph"><p>Server MUST diagnose and abort if capabilities it does not understand
 was sent. Server MUST NOT ignore capabilities that client requested
 and server advertised. As a consequence of these rules, server MUST
 NOT advertise capabilities it does not understand.</p></div>
 <div class="paragraph"><p>The <em>report-status</em> and <em>delete-refs</em> capabilities are sent and
 recognized by the receive-pack (push to server) process.</p></div>
 <div class="paragraph"><p>The <em>ofs-delta</em> capability is sent and recognized by both upload-pack
 and receive-pack protocols.</p></div>
 <div class="paragraph"><p>All other capabilities are only recognized by the upload-pack (fetch
 from server) process.</p></div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="_multi_ack">multi_ack</h2>
 <div class="sectionbody">
 <div class="paragraph"><p>The <em>multi_ack</em> capability allows the server to return "ACK obj-id
 continue" as soon as it finds a commit that it can use as a common
 base, between the client&#8217;s wants and the client&#8217;s have set.</p></div>
 <div class="paragraph"><p>By sending this early, the server can potentially head off the client
 from walking any further down that particular branch of the client&#8217;s
 repository history. The client may still need to walk down other
 branches, sending have lines for those, until the server has a
 complete cut across the DAG, or the client has said "done".</p></div>
 <div class="paragraph"><p>Without multi_ack, a client sends have lines in --date-order until
 the server has found a common base. That means the client will send
 have lines that are already known by the server to be common, because
 they overlap in time with another branch that the server hasn&#8217;t found
 a common base on yet.</p></div>
 <div class="paragraph"><p>For example suppose the client has commits in caps that the server
 doesn&#8217;t and the server has commits in lower case that the client
 doesn&#8217;t, as in the following diagram:</p></div>
 <div class="literalblock">
 <div class="content">
 <pre><code> +---- u ---------------------- x
  / +----- y
  / /
 a -- b -- c -- d -- E -- F
  \
  +--- Q -- R -- S</code></pre>
 </div></div>
 <div class="paragraph"><p>If the client wants x,y and starts out by saying have F,S, the server
 doesn&#8217;t know what F,S is. Eventually the client says "have d" and
 the server sends "ACK d continue" to let the client know to stop
 walking down that line (so don&#8217;t send c-b-a), but it&#8217;s not done yet,
 it needs a base for x. The client keeps going with S-R-Q, until a
 gets reached, at which point the server has a clear base and it all
 ends.</p></div>
 <div class="paragraph"><p>Without multi_ack the client would have sent that c-b-a chain anyway,
 interleaved with S-R-Q.</p></div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="_thin_pack">thin-pack</h2>
 <div class="sectionbody">
 <div class="paragraph"><p>This capability means that the server can send a <em>thin</em> pack, a pack
 which does not contain base objects; if those base objects are available
 on client side. Client requests <em>thin-pack</em> capability when it
 understands how to "thicken" it by adding required delta bases making
 it self-contained.</p></div>
 <div class="paragraph"><p>Client MUST NOT request <em>thin-pack</em> capability if it cannot turn a thin
 pack into a self-contained pack.</p></div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="_side_band_side_band_64k">side-band, side-band-64k</h2>
 <div class="sectionbody">
 <div class="paragraph"><p>This capability means that server can send, and client understand multiplexed
 progress reports and error info interleaved with the packfile itself.</p></div>
 <div class="paragraph"><p>These two options are mutually exclusive. A modern client always
 favors <em>side-band-64k</em>.</p></div>
 <div class="paragraph"><p>Either mode indicates that the packfile data will be streamed broken
 up into packets of up to either 1000 bytes in the case of <em>side_band</em>,
 or 65520 bytes in the case of <em>side_band_64k</em>. Each packet is made up
 of a leading 4-byte pkt-line length of how much data is in the packet,
 followed by a 1-byte stream code, followed by the actual data.</p></div>
 <div class="paragraph"><p>The stream code can be one of:</p></div>
 <div class="literalblock">
 <div class="content">
 <pre><code>1 - pack data
 2 - progress messages
 3 - fatal error message just before stream aborts</code></pre>
 </div></div>
 <div class="paragraph"><p>The "side-band-64k" capability came about as a way for newer clients
 that can handle much larger packets to request packets that are
 actually crammed nearly full, while maintaining backward compatibility
 for the older clients.</p></div>
 <div class="paragraph"><p>Further, with side-band and its up to 1000-byte messages, it&#8217;s actually
 999 bytes of payload and 1 byte for the stream code. With side-band-64k,
 same deal, you have up to 65519 bytes of data and 1 byte for the stream
 code.</p></div>
 <div class="paragraph"><p>The client MUST send only maximum of one of "side-band" and "side-
 band-64k". Server MUST diagnose it as an error if client requests
 both.</p></div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="_ofs_delta">ofs-delta</h2>
 <div class="sectionbody">
 <div class="paragraph"><p>Server can send, and client understand PACKv2 with delta referring to
 its base by position in pack rather than by an obj-id. That is, they can
 send/read OBJ_OFS_DELTA (aka type 6) in a packfile.</p></div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="_shallow">shallow</h2>
 <div class="sectionbody">
 <div class="paragraph"><p>This capability adds "deepen", "shallow" and "unshallow" commands to
 the fetch-pack/upload-pack protocol so clients can request shallow
 clones.</p></div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="_no_progress">no-progress</h2>
 <div class="sectionbody">
 <div class="paragraph"><p>The client was started with "git clone -q" or something, and doesn&#8217;t
 want that side band 2. Basically the client just says "I do not
 wish to receive stream 2 on sideband, so do not send it to me, and if
 you did, I will drop it on the floor anyway". However, the sideband
 channel 3 is still used for error responses.</p></div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="_include_tag">include-tag</h2>
 <div class="sectionbody">
 <div class="paragraph"><p>The <em>include-tag</em> capability is about sending annotated tags if we are
 sending objects they point to. If we pack an object to the client, and
 a tag object points exactly at that object, we pack the tag object too.
 In general this allows a client to get all new annotated tags when it
 fetches a branch, in a single network connection.</p></div>
 <div class="paragraph"><p>Clients MAY always send include-tag, hardcoding it into a request when
 the server advertises this capability. The decision for a client to
 request include-tag only has to do with the client&#8217;s desires for tag
 data, whether or not a server had advertised objects in the
 refs/tags/* namespace.</p></div>
 <div class="paragraph"><p>Servers MUST pack the tags if their referrant is packed and the client
 has requested include-tags.</p></div>
 <div class="paragraph"><p>Clients MUST be prepared for the case where a server has ignored
 include-tag and has not actually sent tags in the pack. In such
 cases the client SHOULD issue a subsequent fetch to acquire the tags
 that include-tag would have otherwise given the client.</p></div>
 <div class="paragraph"><p>The server SHOULD send include-tag, if it supports it, regardless
 of whether or not there are tags available.</p></div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="_report_status">report-status</h2>
 <div class="sectionbody">
 <div class="paragraph"><p>The upload-pack process can receive a <em>report-status</em> capability,
 which tells it that the client wants a report of what happened after
 a packfile upload and reference update. If the pushing client requests
 this capability, after unpacking and updating references the server
 will respond with whether the packfile unpacked successfully and if
 each reference was updated successfully. If any of those were not
 successful, it will send back an error message. See pack-protocol.txt
 for example messages.</p></div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="_delete_refs">delete-refs</h2>
 <div class="sectionbody">
 <div class="paragraph"><p>If the server sends back the <em>delete-refs</em> capability, it means that
 it is capable of accepting a zero-id value as the target
 value of a reference update. It is not sent back by the client, it
 simply informs the client that it can be sent zero-id values
 to delete references.</p></div>
 </div>
 </div>
 </div>
 <div id="footnotes"><hr /></div>
 <div id="footer">
 <div id="footer-text">
 Last updated 2011-11-15 13:45:02 PST
 </div>
 </div>
 </body>
 </html>