PUBLIC MARKS with tags file-format & xml

xFolk Entry 0.4 is a new iteration of the xFolk microformat that is extremely easy to implement. It enables the publication of tagged bookmarks so that they can be harvested on the web and aggregated into folksonomies. As such, xFolk eliminates the need to rely on centralized data repositories to create folksonomies.

a wannabe standard for data formatting, without markup (therefore, not xml-compliant)

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