CS Knowledge Base

OPML is "an XML-based format that allows exchange of outline-structured information between applications running on different operating systems and environments."

[September 16, 2000] Dave Winer (UserLand Software) posted an announcement for a new XML-based format "Outline Processor Markup Language", or OPML, 1.0. "The purpose of this OPML format is to provide a way to exchange information between outliners and Internet services that can be browsed or controlled through an outliner. An 'outline' [in this case] is a tree, where each node contains a set of named attributes with string values. The OPML design goal is to have a transparently simple, self-documenting, extensible and human readable format that's capable of representing a wide variety of data that's easily browsed and edited. As the format evolves this goal will be preserved. It should be possible for a reasonably technical person to fully understand the format with a quick read of a single Web page. OPML 1.0 is the native file format of Radio UserLand, a product in development at UserLand. The specification may be tweaked in response to comments or questions." Background and rationale: "Outlines have been a popular way to organize information on computers for a long time. While the history of outlining software is unclear, a rough timeline is possible. Probably the first outliner was developed by Doug Engelbart, as part of the Augment system in the 1960s. Living Videotext, 1981-87, developed several popular outliners for personal computers. They are archived on a UserLand website, outliners.com. Frontier, first shipped in 1992, is built around outlining. The text, menu and script editors in Frontier are outliners, as is the object database browser. XML 1.0, the format that OPML is based on, is a recommendation of the W3C. Radio UserLand, first shipped in 2000, is an outliner whose native file format is OPML. Outlines can be used for specifications, legal briefs, product plans, presentations, screenplays, directories, diaries, discussion groups, chat systems and stories. Outliners are programs that allow you to read, edit and reorganize outlines. [Online] examples of OPML documents: play list, specification, presentation."

References:

• OPML Web Page

• OPML Specification

• Previous: OPML Web Page

• OPML information on the Atom Wiki

• XML DTD for OPML. Posted by Wayne Steele

• OPML 1.0 DTD from Userland; [cache]

• [September 20, 2001] Scripting News Available in in OPML. "...An advantage of OPML over other forms is that aggregators get the structure of the document, so they can tell when a set of comments are part of a sub-outline, and should be grouped together. It's also possible to add attributes to individual items...

• OPML developers' mailing list

• "OPML and XSLT." By Joshua Allen. "OPML.XSLT is a simple XSLTT transform that converts an OPML document into a collections of DIVs and SPANs suitable for use in browsers. The HTML format retains all information and is suitable for quick, non-lossy transformation back to OPML. It uses the W3C standard XSLT 1.0 and has been tested to work under the nine major XSLL processors available for a variety of platforms, including MSXML3, Apache Xalann, and Oracle XSLL.

• Francis Norton wrote on 19-September-2000: "I've looked at some of the SVG demos at http://www.adobe.com/svg, and an opml->svg transform looks to me like a very interesting little project..."