<!DOCTYPE html>
<html class="client-nojs vector-feature-night-mode-disabled vector-feature-language-in-header-enabled vector-feature-language-in-main-page-header-disabled vector-feature-page-tools-pinned-disabled vector-feature-toc-pinned-clientpref-1 vector-feature-main-menu-pinned-disabled vector-feature-limited-width-clientpref-1 vector-feature-limited-width-content-enabled vector-feature-custom-font-size-clientpref-1 vector-feature-appearance-pinned-clientpref-1 vector-sticky-header-enabled" lang="en" dir="ltr"><head>
<meta charset="UTF-8">
<title>Content reference identifier</title>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<link rel="canonical" href="https://en.wikipedia.org/wiki/Content_reference_identifier"> <link href="./mw/skins.vector.icons.css" rel="stylesheet" type="text/css">
<link href="./mw/skins.vector.search.codex.styles.css" rel="stylesheet" type="text/css">
<link href="./mw/skins.vector.styles.css" rel="stylesheet" type="text/css">
<link href="./mw/user.styles.css" rel="stylesheet" type="text/css">
<meta name="ResourceLoaderDynamicStyles" content="">
<link rel="stylesheet" type="text/css" href="./mw/site.styles.css">
<link rel="stylesheet" type="text/css" href="./mw/noscript.css">
<link rel="stylesheet" type="text/css" href="./footer.css">
<link rel="stylesheet" type="text/css" href="./vector-2022.css">
</head>
<body class="skin--responsive skin-vector skin-vector-search-vue mediawiki ltr sitedir-ltr mw-hide-empty-elt ns-0 ns-subject page-Content_reference_identifier rootpage-Content_reference_identifier skin-vector-2022 action-view">
<div class="mw-page-container">
<div class="mw-page-container-inner">
<div class="mw-content-container">
<main id="content" class="mw-body">
<header class="mw-body-header vector-page-titlebar">
<h1 id="firstHeading" class="firstHeading mw-first-heading">
<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Content reference identifier</span></span>
</h1>
</header>
<a id="top"></a>
<div id="bodyContent" class="vector-body ve-init-mw-desktopArticleTarget-targetContainer" aria-labelledby="firstHeading" data-mw-ve-target-container="">
<div id="mw-content-text" class="mw-body-content mw-content-ltr" lang="en" dir="ltr"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><p class="mw-empty-elt">
</p>
<style data-mw-deduplicate="TemplateStyles:r1305433154">
/* start https://en.wikipedia.org/ */
.mw-parser-output .ambox{border:1px solid #a2a9b1;border-left:10px solid #36c;background-color:#fbfbfb;box-sizing:border-box}.mw-parser-output .ambox+link+.ambox,.mw-parser-output .ambox+link+style+.ambox,.mw-parser-output .ambox+link+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+style+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+link+.ambox{margin-top:-1px}html body.mediawiki .mw-parser-output .ambox.mbox-small-left{margin:4px 1em 4px 0;overflow:hidden;width:238px;border-collapse:collapse;font-size:88%;line-height:1.25em}.mw-parser-output .ambox-speedy{border-left:10px solid #b32424;background-color:#fee7e6}.mw-parser-output .ambox-delete{border-left:10px solid #b32424}.mw-parser-output .ambox-content{border-left:10px solid #f28500}.mw-parser-output .ambox-style{border-left:10px solid #fc3}.mw-parser-output .ambox-move{border-left:10px solid #9932cc}.mw-parser-output .ambox-protection{border-left:10px solid #a2a9b1}.mw-parser-output .ambox .mbox-text{border:none;padding:0.25em 0.5em;width:100%}.mw-parser-output .ambox .mbox-image{border:none;padding:2px 0 2px 0.5em;text-align:center}.mw-parser-output .ambox .mbox-imageright{border:none;padding:2px 0.5em 2px 0;text-align:center}.mw-parser-output .ambox .mbox-empty-cell{border:none;padding:0;width:1px}.mw-parser-output .ambox .mbox-image-div{width:52px}@media(min-width:720px){.mw-parser-output .ambox{margin:0 10%}}@media print{body.ns-0 .mw-parser-output .ambox{display:none!important}}
/* end https://en.wikipedia.org/ */
</style>
<style data-mw-deduplicate="TemplateStyles:r1236090951">
/* start https://en.wikipedia.org/ */
.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}
/* end https://en.wikipedia.org/ */
</style><div role="note" class="hatnote navigation-not-searchable">CRID redirects here. CRID may also refer to a current rail indicator device, a safety device indicating the presence of <a href="Third_rail" title="Third rail">third rail</a> power, or to a <a href="Ring-imaging_Cherenkov_detector" title="Ring-imaging Cherenkov detector">Cherenkov Ring-Imaging Detector</a></div>
<p>A <b>content reference identifier</b> or <b>CRID</b> is a concept from the standardization work done by the <a href="TV-Anytime" title="TV-Anytime">TV-Anytime</a> forum. It is or closely matches the concept of the <a href="Uniform_Resource_Locator" class="mw-redirect" title="Uniform Resource Locator">Uniform Resource Locator</a>, or URL, as used on the <a href="World-Wide_Web" class="mw-redirect" title="World-Wide Web">World-Wide Web</a>:
</p>
<style data-mw-deduplicate="TemplateStyles:r1244412712">
/* start https://en.wikipedia.org/ */
.mw-parser-output .templatequote{overflow:hidden;margin:1em 0;padding:0 32px}.mw-parser-output .templatequotecite{line-height:1.5em;text-align:left;margin-top:0}@media(min-width:500px){.mw-parser-output .templatequotecite{padding-left:1.6em}}
/* end https://en.wikipedia.org/ */
</style><blockquote class="templatequote"><p>A unit of content, in a <a href="Broadcasting" title="Broadcasting">broadcast stream</a>, can be referred to by its globally unique CRID in the same way that a <a href="Webpage" class="mw-redirect" title="Webpage">webpage</a> can be referred to by its globally unique URL on the web.</p></blockquote>
<p>The concept of CRID permits referencing contents unambiguously, regardless of their location, i.e., without knowing specific broadcast information (time, date and channel) or how to obtain them through a network, for instance, by means of a streaming service or by downloading a file from an Internet server.
</p><p>The receiver must be capable of resolving these unambiguous references, i.e. of translating them into specific data that will allow it to obtain the location of that content in order to acquire it. This makes it possible for recording processes to take place without knowing that information, and even without knowing beforehand the duration of the content to be recorded: a complete series by a simple click, a program that has not been scheduled yet, a set of programs grouped by a specific criterion…
</p><p>This framework allows for the separation between the reference to a given content (the CRID) and the necessary information to acquire it, which is called a “locator”. Each CRID may lead to one or more locators which will represent different copies of the same content. They may be identical copies broadcast in different channels or dates, or cost different prices. They may also be distinct copies with different technical parameters such as format or quality.
</p><p>It may also be the case that the resolution process of a CRID provides another CRID as a result (for example, its reference in a different network, where it has an alternative identifier assigned by a different operator) or a set of CRIDs (for instance, if the original CRID represents a TV series, in which case the resolution process would result in the list of CRIDs representing each episode).
</p><p>From the above it can be concluded that provided that a given content can belong to many groups (each possibly defined by distinctive qualities), it is possible that many CRIDs carry the same content. That is, several CRIDs may be resolved into the same locator.
</p><p>A CRID is not exactly a universal, unique and exclusive identifier for a given content. It is closely related to the authority that creates it, to the resolution service provider, and to the content provider in such a way that the same content may have different CRIDs depending on the field in which they are used (for example, a different one for each television operator that has the rights to broadcast the content).
</p>
<meta property="mw:PageProp/toc">
<div class="mw-heading mw-heading2"><h2 id="Format">Format</h2></div>
<p>A CRID is specified much like URLs. In fact, a CRID is a so-called <a href="Uniform_resource_identifier" class="mw-redirect" title="Uniform resource identifier">URI</a>. Typically, the content creator, the broadcaster or a third party will use their <a href="Domain_name_system" class="mw-redirect" title="Domain name system">DNS</a>-names in a combination with a product-specific name to create globally unique CRIDs. That is, the syntax of a CRID is:
</p>
<pre>crid://authority/data
</pre>
<p>The <i>authority</i> field represents the entity that created the CRID and its format is that of a DNS name. The <i>data</i> field represents a string of characters that will unambiguously identify the content within the authority scope (it is a string of characters assigned by the authority itself).
</p><p>As an example, let's assume that <a href="BBC" title="BBC">BBC</a> wanted to make a CRID for (all the programs of) the Olympics in China. It may have looked something like this
</p>
<pre>crid://bbc.co.uk/olympics/2008/
</pre>
<p>This would be a group CRID, that is, a CRID representing a group of contents. Then, to refer to a specific event – such as the women's shot-put final – they could have used the following inside their metadata.
</p>
<pre>crid://bbc.co.uk/olympics/2008/final/shotput/women
</pre>
<p>Currently, four types of CRIDs are playing a major role in some <a href="Unidirectional_networks" class="mw-redirect" title="Unidirectional networks">unidirectional</a> television networks: programme CRID, series CRID, group CRID, and recommendation CRID. One of the most important applications of CRIDs is the so-called series link recording function (SL) of modern digital video recorders (<a href="Digital_video_recorder" title="Digital video recorder">DVR</a>, <a href="Personal_video_recorder" class="mw-redirect" title="Personal video recorder">PVR</a>).
</p><p>In turn, a locator is a string of characters that contains all the necessary information for a receiver to find and acquire a given content, whether it is received through a transport stream, located in local storage, downloaded as a file from an Internet server, or through a streaming service. For example, a DVB locator will include all the necessary parameters to identify a specific content within a transport stream: network, transport stream, service, table and/or event identifiers.
</p><p>The locators' format, as established in TV-Anytime, is quite generic and simple, and corresponds to:
</p>
<pre>[transport-mechanism]:[specific-data]
</pre>
<p>The first part of the locator’s format (the transport mechanism) must be a string of characters that is unique for each mechanism (transport stream, local file, HTTP Internet access…). The second part must be unambiguous only within the scope of a given transport mechanism and will be standardized by the organism in charge of the regulation of the mechanism itself.
For instance, a DVB locator to identify a content within the transport stream of networks that follow this standard would be:
</p>
<pre>dvb://112.4a2.5ec;2d22~20121212T220000Z—PT01H30M
</pre>
<p>which would indicate a content (identified by the string “2d22”) that airs on a channel available on a DVB network identified by the address “112.4a2.5ec” (network “112”, transport stream “4a2” and service “5ec”), on 12 December 2012 at 10 p.m. and with a duration of 90 minutes.
</p>
<div class="mw-heading mw-heading2"><h2 id="The_location_resolution_process">The location resolution process</h2></div>
<p>The location resolution process is the procedure by which, starting from the CRID of a given content, one or several locators of that content are obtained. Resolving a CRID can be a direct process, which leads immediately to one or many locators, or it may also happen that in the first place one or many intermediate CRIDs are returned, which must undergo the same procedure to finally obtain one or several locators.
</p><p>This procedure involves some information elements, among which we find two structures named resolving authority record (RAR) and ContentReferencingTable, respectively. Consulting them repeatedly will take the receiver from a CRID to one or many locators that will allow it to acquire the content.
</p><p><b>The RAR table</b>
</p><p>The RAR table is one or many data structures that provide the receiver, for each authority that submits CRIDs, information on the corresponding resolution service provider. Among other things, it informs about which mechanism is used to provide information to resolve the CRIDs from each authority. That is, one or many RAR records must exist for each authority that indicate the receiver where it has to go to resolve the CRIDs of that particular authority.
</p><p>For example, in the record of the figure (expressed by means of a XML structure, according to the XML Schema defined in the TV-Anytime) there is an authority called “tve.es”, whose resolution service provider is the entity “rtve.es”, available on the URL "http://tva.rtve.es/locres/tve", which means there is resolution information in that URL.
</p>
<p>These RAR records will have reached the receiver in an indefinite form, unimportant for the TV-Anytime specification, which will depend on the specific transport mechanism of the network to which the receiver is connected. Each family of standards that regulates distribution networks (DVB, ATSC, ISDB, IPTV...) will have previously defined such procedure, which will be used by devices certified according to those standards.
</p><p><b>The ContentReferencingTable table</b>
</p><p>The second structure involved in the location resolution process is a proper resolution table which, given a content's CRID, returns one or several locators that enable the receiver to access an instance of that content, or one or many CRIDs that allow it to move forward in the resolution process.
</p><p>The figure shows an example of this second structure, an XML document according to the specifications of the XML Schema defined in TV-Anytime. In it, several sections are included (<Result> elements) that structure the information that describes each resolution case.
</p>
<p>The first one declares how a CRID (crid://tv.com/Friends/all), which corresponds to a group content that encompasses several episodes (two) of the “Friends” series is resolved. The result of the resolution process provides two new CRIDs each of them corresponding to one of the two episodes.
</p><p>The second <Result> element resolves the CRID of the first episode of the first season. The result of the resolution process is two DVB locators. The “acquire” attribute with “any” value indicates that any of them are good (the second one is a repetition broadcast a week later).
</p><p>The third <Result> element gives information about the second episode. It indicates that it cannot be resolved yet (“status” attribute with the “cannot yet resolve” value), indicating a date on which the request for resolution information must be repeated.
</p><p><b>The process</b>
</p><p>Once the user has selected a given content (identified by the corresponding CRID) to perform some action upon it, the receiver begins the location resolution process that shall lead to specific location information that allows access to a copy of the content.
</p><p>This procedure depends mainly on the receiver’s connectivity. It is possible to make a basic distinction between unidirectional networks, where the receiver can only receive information through the broadcast channel, and bidirectional networks, where there is also a return channel through which the receiver can communicate with the outside (typically an Internet access).
</p><p>For receivers connected only to a broadcast channel, it is clear that the resolution information must come directly from that channel, or be available somehow in an existing local storage system. After selecting a CRID, the first thing the receiver needs to do is check the information about where to find the resolution table. For this, it must find a RAR record associated with the authority of the selected CRID.
</p><p>Once a RAR record corresponding to that authority is found, the receiver will know, by referring to the URL field, where to access (or, in this case, where to listen) to obtain the resolution information.
</p><p>The information that will receive through that access point will consist of a message for each of the consulted CRIDs (for example, a <Result> element in the ContentReferencingTable).
</p>
<div class="mw-heading mw-heading2"><h2 id="In_web_casting">In web casting</h2></div>
<p>To make the CRID even more globally available the <a href="IETF" class="mw-redirect" title="IETF">IETF</a> will publish a request for comments specifying the use of the CRID over the web. This will allow consumer devices to hook up to content provider servers, much like current browsers look up webservers, requesting content by CRID.
</p><p>In May 2005, an Informational RFC, <a rel="nofollow" class="external text" href="http://tools.ietf.org/html/rfc4078">No 4078</a>, was published as the start of this work.
</p><p>The long-term goal is that CRIDs should be available for use by <a href="Cell_phones" class="mw-redirect" title="Cell phones">cell phones</a>, <a href="Personal_digital_assistant" title="Personal digital assistant">PDAs</a>, <a href="Digital_television" title="Digital television">digital TV</a> <a href="Set-top_box" title="Set-top box">receivers</a> and other <a href="Consumer_electronics" title="Consumer electronics">consumer devices</a> for fetching content, either from a broadcast stream or over <a href="IP_network" class="mw-redirect" title="IP network">IP networks</a>.
</p>
<div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2></div>
<ul><li><a href="BBC_Programme_Identifier" title="BBC Programme Identifier">BBC Programme Identifier</a></li></ul>
<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>
<ul><li><a rel="nofollow" class="external text" href="http://ftp.rfc-editor.org/in-notes/pdfrfc/rfc4078.txt.pdf">RFC 4078 (PDF)</a> Accessed 27 October 2011</li>
<li><a rel="nofollow" class="external text" href="http://ftp.rfc-editor.org/in-notes/rfc4078.txt">RFC 4078 (TXT)</a> Accessed 27 October 2011</li>
<li><a rel="nofollow" class="external text" href="http://www.etsi.org/deliver/etsi_ts/102800_102899/10282202/01.04.01_60/ts_10282202v010401p.pdf">ETSI TS 102 822-2 V1.4.1 (2007–11), Page 19, Section 5: "TV-Anytime content referencing scenarios"</a> Accessed 3 December 2012</li>
<li><a rel="nofollow" class="external text" href="http://www.etsi.org/deliver/etsi_ts/102800_102899/10282204/01.07.01_60/ts_10282204v010701p.pdf">ETSI TS 102 822-4 V1.7.1 (2012–12), Page 13, Section 8: "CRID"</a> Accessed 9 January 2013</li>
<li><a rel="nofollow" class="external text" href="http://www.etsi.org/deliver/etsi_ts/102300_102399/102323/01.05.01_60/ts_102323v010501p.pdf">ETSI TS 102 323 V1.5.1 (2012-01), Page 27, Section 6: "CRIDs and other URIs in DVB networks"</a> Accessed 1 March 2012</li></ul>
<div class="navbox-styles"><style data-mw-deduplicate="TemplateStyles:r1129693374">
/* start https://en.wikipedia.org/ */
.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output .hlist.inline,.mw-parser-output .hlist.inline dl,.mw-parser-output .hlist.inline ol,.mw-parser-output .hlist.inline ul,.mw-parser-output .hlist dl dl,.mw-parser-output .hlist dl ol,.mw-parser-output .hlist dl ul,.mw-parser-output .hlist ol dl,.mw-parser-output .hlist ol ol,.mw-parser-output .hlist ol ul,.mw-parser-output .hlist ul dl,.mw-parser-output .hlist ul ol,.mw-parser-output .hlist ul ul{display:inline}.mw-parser-output .hlist .mw-empty-li{display:none}.mw-parser-output .hlist dt::after{content:": "}.mw-parser-output .hlist dd::after,.mw-parser-output .hlist li::after{content:" · ";font-weight:bold}.mw-parser-output .hlist dd:last-child::after,.mw-parser-output .hlist dt:last-child::after,.mw-parser-output .hlist li:last-child::after{content:none}.mw-parser-output .hlist dd dd:first-child::before,.mw-parser-output .hlist dd dt:first-child::before,.mw-parser-output .hlist dd li:first-child::before,.mw-parser-output .hlist dt dd:first-child::before,.mw-parser-output .hlist dt dt:first-child::before,.mw-parser-output .hlist dt li:first-child::before,.mw-parser-output .hlist li dd:first-child::before,.mw-parser-output .hlist li dt:first-child::before,.mw-parser-output .hlist li li:first-child::before{content:" (";font-weight:normal}.mw-parser-output .hlist dd dd:last-child::after,.mw-parser-output .hlist dd dt:last-child::after,.mw-parser-output .hlist dd li:last-child::after,.mw-parser-output .hlist dt dd:last-child::after,.mw-parser-output .hlist dt dt:last-child::after,.mw-parser-output .hlist dt li:last-child::after,.mw-parser-output .hlist li dd:last-child::after,.mw-parser-output .hlist li dt:last-child::after,.mw-parser-output .hlist li li:last-child::after{content:")";font-weight:normal}.mw-parser-output .hlist ol{counter-reset:listitem}.mw-parser-output .hlist ol>li{counter-increment:listitem}.mw-parser-output .hlist ol>li::before{content:" "counter(listitem)"\a0 "}.mw-parser-output .hlist dd ol>li:first-child::before,.mw-parser-output .hlist dt ol>li:first-child::before,.mw-parser-output .hlist li ol>li:first-child::before{content:" ("counter(listitem)"\a0 "}
/* end https://en.wikipedia.org/ */
</style><style data-mw-deduplicate="TemplateStyles:r1236075235">
/* start https://en.wikipedia.org/ */
.mw-parser-output .navbox{box-sizing:border-box;border:1px solid #a2a9b1;width:100%;clear:both;font-size:88%;text-align:center;padding:1px;margin:1em auto 0}.mw-parser-output .navbox .navbox{margin-top:0}.mw-parser-output .navbox+.navbox,.mw-parser-output .navbox+.navbox-styles+.navbox{margin-top:-1px}.mw-parser-output .navbox-inner,.mw-parser-output .navbox-subgroup{width:100%}.mw-parser-output .navbox-group,.mw-parser-output .navbox-title,.mw-parser-output .navbox-abovebelow{padding:0.25em 1em;line-height:1.5em;text-align:center}.mw-parser-output .navbox-group{white-space:nowrap;text-align:right}.mw-parser-output .navbox,.mw-parser-output .navbox-subgroup{background-color:#fdfdfd}.mw-parser-output .navbox-list{line-height:1.5em;border-color:#fdfdfd}.mw-parser-output .navbox-list-with-group{text-align:left;border-left-width:2px;border-left-style:solid}.mw-parser-output tr+tr>.navbox-abovebelow,.mw-parser-output tr+tr>.navbox-group,.mw-parser-output tr+tr>.navbox-image,.mw-parser-output tr+tr>.navbox-list{border-top:2px solid #fdfdfd}.mw-parser-output .navbox-title{background-color:#ccf}.mw-parser-output .navbox-abovebelow,.mw-parser-output .navbox-group,.mw-parser-output .navbox-subgroup .navbox-title{background-color:#ddf}.mw-parser-output .navbox-subgroup .navbox-group,.mw-parser-output .navbox-subgroup .navbox-abovebelow{background-color:#e6e6ff}.mw-parser-output .navbox-even{background-color:#f7f7f7}.mw-parser-output .navbox-odd{background-color:transparent}.mw-parser-output .navbox .hlist td dl,.mw-parser-output .navbox .hlist td ol,.mw-parser-output .navbox .hlist td ul,.mw-parser-output .navbox td.hlist dl,.mw-parser-output .navbox td.hlist ol,.mw-parser-output .navbox td.hlist ul{padding:0.125em 0}.mw-parser-output .navbox .navbar{display:block;font-size:100%}.mw-parser-output .navbox-title .navbar{float:left;text-align:left;margin-right:0.5em}body.skin--responsive .mw-parser-output .navbox-image img{max-width:none!important}@media print{body.ns-0 .mw-parser-output .navbox{display:none!important}}
/* end https://en.wikipedia.org/ */
</style></div><div role="navigation" class="navbox" aria-labelledby="Uniform_Resource_Identifier_(URI)_schemes138" style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><style data-mw-deduplicate="TemplateStyles:r1239400231">
/* start https://en.wikipedia.org/ */
.mw-parser-output .navbar{display:inline;font-size:88%;font-weight:normal}.mw-parser-output .navbar-collapse{float:left;text-align:left}.mw-parser-output .navbar-boxtext{word-spacing:0}.mw-parser-output .navbar ul{display:inline-block;white-space:nowrap;line-height:inherit}.mw-parser-output .navbar-brackets::before{margin-right:-0.125em;content:"[ "}.mw-parser-output .navbar-brackets::after{margin-left:-0.125em;content:" ]"}.mw-parser-output .navbar li{word-spacing:-0.125em}.mw-parser-output .navbar a>span,.mw-parser-output .navbar a>abbr{text-decoration:inherit}.mw-parser-output .navbar-mini abbr{font-variant:small-caps;border-bottom:none;text-decoration:none;cursor:inherit}.mw-parser-output .navbar-ct-full{font-size:114%;margin:0 7em}.mw-parser-output .navbar-ct-mini{font-size:114%;margin:0 4em}html.skin-theme-clientpref-night .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}@media(prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}}@media print{.mw-parser-output .navbar{display:none!important}}
/* end https://en.wikipedia.org/ */
</style><div id="Uniform_Resource_Identifier_(URI)_schemes138" style="font-size:114%;margin:0 4em"><a href="List_of_URI_schemes" title="List of URI schemes">Uniform Resource Identifier (URI) schemes</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Official</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">
<ul><li><a href="About_URI_scheme" title="About URI scheme">about</a></li>
<li><a href="Acct_URI_scheme" title="Acct URI scheme">acct</a></li>
<li><a href="Data_URI_scheme" title="Data URI scheme">data</a></li>
<li><a href="File_URI_scheme" title="File URI scheme">file</a></li>
<li><a href="File_Transfer_Protocol" title="File Transfer Protocol">ftp</a></li>
<li><a href="Geo_URI_scheme" title="Geo URI scheme">geo</a></li>
<li><a href="Gopher_(protocol)" title="Gopher (protocol)">gopher</a></li>
<li><a href="HTTP#Technical_overview" title="HTTP">http</a></li>
<li><a href="HTTPS" title="HTTPS">https</a></li>
<li><a href="Info_URI_scheme" title="Info URI scheme">info</a></li>
<li><a href="Lightweight_Directory_Access_Protocol#URI_scheme" title="Lightweight Directory Access Protocol">ldap</a></li>
<li><a href="Mailto" title="Mailto">mailto</a></li>
<li><a href="Network_File_System" title="Network File System">nfs</a></li>
<li><a href="Network_News_Transfer_Protocol" title="Network News Transfer Protocol">nntp</a></li>
<li><a href="SIP_URI_scheme" title="SIP URI scheme">sip / sips</a></li>
<li><a href="Tag_URI_scheme" title="Tag URI scheme">tag</a></li>
<li><a href="Telnet" title="Telnet">telnet</a></li>
<li><a href="Uniform_Resource_Name" title="Uniform Resource Name">urn</a></li>
<li><a href="View-source_URI_scheme" title="View-source URI scheme">view-source</a></li>
<li><a href="WebSocket#Overview" title="WebSocket">ws / wss</a></li>
<li><a href="XMPP" title="XMPP">xmpp</a></li></ul>
</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Unofficial</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">
<ul><li><a href="Hyper_Text_Coffee_Pot_Control_Protocol#Commands_and_replies" title="Hyper Text Coffee Pot Control Protocol">coffee</a></li>
<li><a href="Ed2k_URI_scheme" title="Ed2k URI scheme">ed2k</a></li>
<li><a href="Gemini_(protocol)" title="Gemini (protocol)">gemini</a></li>
<li><a href="Feed_URI_scheme" title="Feed URI scheme">feed</a></li>
<li><a href="Finger_(protocol)" title="Finger (protocol)">finger</a></li>
<li><a href="Internet_Relay_Chat" class="mw-redirect" title="Internet Relay Chat">irc / irc6 / ircs</a></li>
<li><a href="Lightweight_Directory_Access_Protocol#URI_scheme" title="Lightweight Directory Access Protocol">ldaps</a></li>
<li><a href="Magnet_URI_scheme" title="Magnet URI scheme">magnet</a></li>
<li><a href="Rsync" title="Rsync">rsync</a></li>
<li><a href="Yahoo!_Messenger" class="mw-redirect" title="Yahoo! Messenger">ymsgr</a></li></ul>
</div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div><a href="List_of_network_protocols_(OSI_model)" title="List of network protocols (OSI model)">Protocol list</a></div></td></tr></tbody></table></div></div><!--htdig_noindex--><div><div class="zim-footer">
This article is issued from <a class="external text" title="Last edited on 2025-02-25" href="https://en.wikipedia.org/wiki/?title=Content_reference_identifier&oldid=1277552374">Wikipedia</a>. The text is available under <a class="external text" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en">Creative Commons Attribution-Share Alike 4.0</a> unless otherwise noted. Additional terms may apply for the media files.
</div>
</div><!--/htdig_noindex--></div>
</div>
</main>
</div>
</div>
</div>
</body></html>