A communiqué from Peter Van Dijck announces the version 1.0 release of the XFML Core - eXchangeable Faceted Metadata Language. XFML Core "is an open XML format for publishing and sharing hierarchical faceted metadata and indexing efforts. XFML is a model to express topics, organised in hierarchies or trees within mutually exclusive containers called facets. It also expresses indexing efforts: metadata you have assigned to pages. It lets you publish this information in an open, XML based format. Finally, XFML lets you build connections between different XFML maps, by indicating that a topic in one map is equal to a topic in another map (we call this connecting topics), or that a topic is described on a certain resource (a webpage usually; we call this published subject indicators). Facetmap, an application to browse faceted metadata, was the first application to import XFML... The real power of XFML lies in the concept of connecting topics. This allows you to reuse indexing efforts. It means you don't have to index the entire web yourself, you can reuse parts of other XFML maps. Metadata authoring applications that take advantage of this concept are being developed."

From the XFML Core specification:

XFML lets you exchange hierarchical faceted metadata. It also lets you indicate topics in different published XFML documents are equal, thus allowing you to reuse indexing efforts.

XFML borrows many ideas from Topicmaps, a format you should check out if you like the ideas behind XFML but are frustrated with its limitations...

The XFML specification explains what XFML is, consists of three things: (1) a bunch of concepts, i.e., a conceptual model; (2) an XML format for expressing these concepts; (3) a set of processing instructions that explain how applications should work with XFML data.

The Core value proposition of XFML Core is that it lets you share and reuse indexing efforts by publishing your metadata, without needing any kind of central or distributed definition of your topics. Quality indexing is hard -- reusing indexing efforts will make metadata more useful. This is important: with XFML there is no centrally defined set of metadata. Each author defines their own facets and topics. XFML can get away with not having a central store of metadata because it lets authors connect individual topics between two specific maps..

XFML Core also provides a simple format to share and reuse faceted metadata hierarchies (the topics and facets). If you export XFML, you can import it in a variety of faceted metadata browsing applications that support XFML like Facetmap.