Katy Ginger from DLESE has published an XML Schema Document for validating OPML 2.0.
Deep Notes, Mac OS X, Freeware single pane.
TKOutline is an outliner for Windows, Linux and Mac OS X similar to OmniOutliner.
(RFC 822 has been superseded by RFC 2822 then RFC 5322.) In general, date and time formats should be represented according to RFC 3339. How to open OPML file format(Outline Processor Markup Language File)Problems with opening OPML files occur very often among users.
The windowXXX elements define the position and size of the display window. expansionState contains a comma-separated list of line numbers that should be expanded on display. dateCreated and dateModified contents conform to the date-time format specified in RFC 822. May include any of these optional elements: title, dateCreated, dateModified, ownerName, ownerEmail, expansionState, vertScrollState, windowTop, windowLeft, windowBottom, windowRight. The keys to editting OPML or XML in buzz are the keys that insert, move, and edit elements. It must contain the version attribute and one head and one body element. Buzz runs on Mac OS X, Windows, Linux, iPaq and Palm OS via Plucker. The XML elements in an OPML document are: