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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 Extensible Markup Language (XML) is a W3C-recommended general-purpose markup language for creating special-purpose markup languages, capable of describing many different kinds of data. ...
A client-side blogging software package from UserLand Software, including an RSS aggregator, outliner and scripting language. ...
An outliner is a special text editor that allows the grouping of text in sections that are organized in a tree data structure (hierarchy) of concepts, an outline. ...
RSS is a family of XML dialects for Web syndication used by (among other things) news websites and weblogs. ...
An aggregator or news aggregator is a type of software that retrieves syndicated Web content that is supplied in the form of a web feed (RSS, Atom and other XML formats), and that are published by weblogs, podcasts, vlogs, and mainstream mass media websites. ...
The OPML specification defines an outline as a hierarchical, ordered list of arbitrary elements. The specification is fairly open which makes it suitable for many types of list data.
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.
Metadata is data about data. ...
Wikipedia does not yet have an article with this exact name. ...
Shortcomings of OPML - OPML stores data in XML attributes, which violates a common XML design principle.
- Generally, it is better to store data in elements
- Principles of XML design: When to use elements versus attributes
- Information about OPML items cannot itself be hierarchically marked up (ironically), due to the use of attributes to store that information.
- The RFC-822 date format is considered obsolete, and amongst other things permits the representation of years as two digits. (RFC-822 has been superseded by RFC-2822)
- Because "expansionState" is recorded independently of the outline elements:
- The expansion state of the children of collapsed nodes can not be stored
- When an outline element is expanded, collapsed, added, deleted or moved, the expansion state of all elements below it must be recalculated
- 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.
Validating OPML Dave Winer has made a request for comments on a proposal for validating OPML, and released a beta OPML validator. Dave Winer Dave Winer (b. ...
Example OPML documents
Alternative specifications OPML is being used more widely because of its ties to RSS. It has also been incorporated into PIM applications. A personal information manager (PIM) is a type of application software that functions as a personal organizer. ...
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. OML (Outline Markup Language) is a specification designed to build upon the concepts found in OPML, with the goal of fixing some of its limitations. ...
Another specification that has been proposed is XOXO. XOXO treats textual content as an XML element rather than an XML "attribute". XOXO is easier than OPML to code by hand in a text editor, since it can be easily previewed in any web browser. XOXO (Extensible Open XHTML Outlines) is an XML format for outlines built from XHTML modularization. ...
Software support - Omni Outliner for Mac OS X can open, edit, and save files in the OPML format.
- OPML Editor is a simple editor for both Mac OS X and Windows.
- Most newsfeed aggregators, including the Firefox and Safari web browsers, can import and export OPML lists of RSS feeds.
- Taskable lets users browse OPML directories from the Windows taskbar.
- Opmlmanager an online opml-editor and -hosting service
- OpmlSearch Search exclusively within OPML files
- OpmlWorkstation Online OPML creation and hosting - includes security and group editing
See also Dave Winer Dave Winer (b. ...
The following is a list of content syndication markup languages. ...
XOXO (Extensible Open XHTML Outlines) is an XML format for outlines built from XHTML modularization. ...
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