OPML
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OPML (Outline Processor Markup Language) is an XML format for outlines. Originally developed by Radio UserLand as a native file format for an outliner application it has since been adopted for other uses, the most common being to exchange lists of RSS feeds between RSS aggregators.
The OPML specification defines an outline as a hierarchical, ordered list of arbritrary elements. The specification is fairly open which makes it suitable for many types of list data.
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XML format
The XML elements in an OPML document are:
- <opml version="1.0">
- This is the root element. It must contain the version attribute and one head and one body element
- <head>
- Contains metadata. May include any of these optional elements: title, dateCreated, dateModified, ownerName, ownerEmail, expansionState, vertScrollState, windowTop, windowLeft, windowBottom, windowRight. Each element is a simple text element. dateCreated and dateModified contents conform to the date-time format specified in RFC 822. expansionState contains a comma-separated list of line numbers that should be expanded on display. The windowXXX elements define the position and size of the display window. An OPML processor may ignore all the head 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 one or more outline elements
- <outline>
- Represents a line in the outline. May contain any number of arbitrary attributes. Common attributes include text and type. The outline element may contain any number of outline sub-elements.
Example OPML documents
- Play list (http://static.userland.com/gems/radiodiscuss/playlist.opml)
- Specification (http://static.userland.com/gems/radiodiscuss/specification.opml)
- Presentation (http://static.userland.com/gems/radiodiscuss/presentation.opml)
- Directory (http://radio.weblogs.com/0001000/gems/publications.opml)
- XML feed list (http://www.scripting.com/feeds/top100.opml) (e.g. blogroll)
Alternative specifications
OPML is being used more widely because of its ties to RSS. It has also been incorporated into PIM applications.
Alternative specifications have been proposed. One such specification is OML. While very similar to OPML, OML forces a separation between data presentation and content; it also treats textual content as an XML element. OPML, by contrast, treats textual content as an XML attribute, which limits its extensibility and precludes the possibility of nested XML elements within textual content, but makes OPML somewhat simpler to code by hand in a text editor.
See also
External links
- What is OPML? (http://www.opml.org/)
- How to create a directory in Radio's Outliner (http://radio.outliners.com/directoryOutliner)
- Share Your OPML! (http://feeds.scripting.com)
- OPML Resources (http://loadaveragezero.com/app/drx/Data_Formats/Markup_Languages/XML/OPML)de:OPML