The
OPML format is very flexible, so flexible that it lacks any defined standard attribute names other than text [title] and a few dates (such as created and modified) which is why we felt that
OML was more appropriate for Ultra Recall.
Some advantages of OML (in our humble opinion) are that binary data such as icons and the actual documents can be exported and definitively referenced by the outputted xml, and can be fully re-consumed by Ultra Recall allowing it be used as a human readable backup format.
A few limitations of Ultra Recall version 1.3b and previous prevent valid opml from being exported by that version, but the 1.4 beta
[download here] has been updated to rectify these problems and can export valid opml by unchecking all the attributes in the xml export dialog page, which will then export only text and the dates defined by the opml standard (which are always exported). This obviously does not export significant parts of the data stored by Ultra Recall but should be consumable by OPML compatible applications.
The obviously beta issues apply: ensure you backup your .urd files before converting (once converted they cannot be opened by the current version) and remember that beta applications contain bugs which may or not affect data integrity and usage (the beta is improving but not yet perfect 
).