Pierre,
Work is ongoing to produce a standard vocabulary and an exchange schema (as well as supporting documents), hopefully in time for presentation at ORM2010 in Crete.
The current draft schema proposal has some significant differences from the one Terry presented last year, and those differences, plus further work to incorporate other fact-oriented methodologies, will take some time to resolve.
If you're in need of a metamodel for reference purposes, I have two published. My actual metamodel (used to generate code in support of CQL) is available in the examples index of my website at http://dataconstellation.com/ActiveFacts/examples/index.shtml, and my intended model (terminology and verbalisation corrections) at http://github.com/cjheath/activefacts/blob/master/examples/norma/MetamodelNext.orm
I hope you find those useful.