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OPML
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<h2 id="xml-format">XML format</h2> <p>The XML elements in an OPML document are: </p> <opml version="1.0"> This is the root element. It must contain the version attribute and one <i>head</i> and one <i>body</i> element. <head> Contains <a href="/facts/Metadata_(computing)/qt35z79C">metadata</a>. May include any of these optional elements: <i>title</i>, <i>dateCreated</i>, <i>dateModified</i>, <i>ownerName</i>, <i>ownerEmail</i>, <i>expansionState</i>, <i> vertScrollState</i>, <i>windowTop</i>, <i>windowLeft</i>, <i>windowBottom</i>, <i>windowRight</i>. Each element is a simple text element. <i>dateCreated</i> and <i>dateModified</i> contents conform to the date-time format specified in <a href="/facts/RFC_(identifier)/esftTvE7">RFC</a> <a href="https://www.rfc-editor.org/rfc/rfc822">822</a>. <i>expansionState</i> contains a comma-separated list of line numbers that should be expanded on display. The <i>windowXXX</i> elements define the position and size of the display window. An OPML processor may ignore all the <i>head</i> sub-elements. If the outline is opened inside another outline then the processor must ignore the window elements. <body> Contains the content of the outline. Must have at least one <i>outline</i> element. <outline> Represents a line in the outline. May contain any number of arbitrary attributes. Common attributes include <i>text</i> and <i>type</i>. The outline element may contain any number of <i>outline</i> sub-elements. <h2 id="criticism">Criticism</h2> <ol><li>The <a href="/facts/RFC_822/6pD9GLtI">RFC 822</a> date format is considered obsolete, and amongst other things permits the representation of years as two digits. (RFC 822 has been superseded by <a href="/facts/RFC_2822/6pD9GLtI">RFC 2822</a> then <a href="/facts/RFC_5322/6pD9GLtI">RFC 5322</a>.) In general, date and time formats should be represented according to <a href="/facts/RFC_3339/4N8kykG9">RFC 3339</a>.</li> <li>Due to the semantics of the "expansionState" attribute: <ul><li>The expansion state of the children of collapsed nodes cannot be stored</li> <li>When an outline element is expanded, collapsed, added, deleted or moved, the expansion state of all elements below it must be recalculated</li></ul></li> <li>Due to the arbitrary nature of the "type" attribute, and the acceptance of arbitrary attributes on "outline" elements, interoperability of OPML documents relies almost entirely on the undocumented conventions of content producers.</li> <li>MIME types aren't clear; text/xml usually merely identifies the document as having XML content, while text/x-opml does not specify that the document is XML since it lacks the <a href="/facts/%252Bxml/clNgUfWk">+xml</a> suffix.</li></ol> <p><a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> </p> <h2 id="validation">Validation</h2> <p><a href="/facts/Dave_Winer/HGEn6245">Dave Winer</a>, the founder and CEO of Userland, has made a request for comments on a <a href="https://web.archive.org/web/20051024010033/http://www.opml.org/guidelinesForValidation">proposal for validating OPML</a> and released a beta <a href="https://web.archive.org/web/20051102000206/http://validator.opml.org/">OPML validator</a>. </p><p>Katy Ginger from DLESE has published <a href="https://web.archive.org/web/20070910025930/http://www.dlese.org/Metadata/opml/2.0/index.htm">an XML Schema Document</a> for validating OPML 2.0. There is also a <a href="http://static.userland.com/gems/radiodiscuss/opmlDtd.txt">DTD available for OPML 1.0</a>. </p> <h2 id="alternative-specifications">Alternative specifications</h2> <p class="note">Main article: <a href="/facts/List_of_content_syndication_markup_languages/3kfk5tIA">List of content syndication markup languages</a></p> <p>Alternative specifications have been proposed, notably these include <a href="/facts/OML_(computer_format)/rUQ5TtLk">OML</a>, <a href="/facts/XOXO_(microformat)/pEPkRxmR">XOXO</a> and <a href="/facts/XBEL/zu3K0tBM">XBEL</a>. </p> <ul><li><a href="/facts/OML_(computer_format)/rUQ5TtLk">OML</a> – Outline Markup Language</li> <li><a href="/facts/XOXO_(microformat)/pEPkRxmR">XOXO</a> – Extensible Open XHTML Outlines</li> <li><a href="/facts/XBEL/zu3K0tBM">XBEL</a> – XML Bookmark Exchange Language</li></ul> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Data_portability/a9UzeKer">Data portability</a></li> <li><a href="/facts/Attention_Profiling_Mark-up_Language/49rKEKPn">APML</a> – Attention Profiling Mark-up Language</li> <li><a href="/facts/Feed_icon/reBfT1GS">Feed icon</a></li> <li><a href="/facts/Share_icon/vGNGqJH6">Share icon</a></li></ul> <h2 id="external-links">External links</h2> <ul><li><a href="https://web.archive.org/web/20160304125338/http://dev.opml.org/spec1.html">OPML 1.0 Specification</a> at the <a href="/facts/Wayback_Machine/nmQ3a6JC">Wayback Machine</a> (archived 2016-03-04)</li> <li><a href="http://dev.opml.org/spec2.html">OPML 2.0 Specification</a></li> <li><a href="http://home.opml.org/">OPML Editor app</a></li> <li><a href="http://www.opmlicons.com/">OPML Icon Files</a></li> <li><a href="http://codebeautify.org/opmlviewer">OPML Viewer-Editor</a></li> <li><a href="http://www.whiterocksoftware.com/2020/07/opml-file-viewer.html">OPML Viewer</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>"OPML 2.0 Specification". Retrieved 18 March 2014. <a href="http://dev.opml.org/spec2.html" target="_blank">http://dev.opml.org/spec2.html</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Fisher, Tim (12 March 2022). "How to Open, Edit, and Convert OPML Files". Lifewire. Retrieved 5 July 2023. <a href="https://www.lifewire.com/opml-file-2622105" target="_blank">https://www.lifewire.com/opml-file-2622105</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>"How to Subscribe to News Feeds and Blogs | Thunderbird Help". support.mozilla.org. Retrieved 11 June 2019. <a href="https://support.mozilla.org/en-US/kb/how-subscribe-news-feeds-and-blogs" target="_blank">https://support.mozilla.org/en-US/kb/how-subscribe-news-feeds-and-blogs</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Fisher, Tim (12 March 2022). "How to Open, Edit, and Convert OPML Files". Lifewire. Retrieved 5 July 2023. <a href="https://www.lifewire.com/opml-file-2622105" target="_blank">https://www.lifewire.com/opml-file-2622105</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>"RFC 5322". RFC editor. Retrieved 21 September 2023. <a href="https://www.rfc-editor.org/rfc/rfc5322" target="_blank">https://www.rfc-editor.org/rfc/rfc5322</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> </ol>