Our first idea have been laid down in a paper presented at ASM'04.

A complete definition of the AsmM metamodel can be found in:

A. Gargantini, E. Riccobene, and P. Scandurra. Metamodelling a Formal Method: Applying MDE to Abstract State Machines. Technical Report 97, DTI Dept., University of Milan, November 2006. [link]

Here you find:

• The AsmM Abstract Syntax (the metamodel)
  

  • The ecore  file for the AsmM
    
  • (not yet in the metamodel, with some errors) The OCL constraints edited by OCLE
    

From the AsmM we have derived the XMI format and the java EMF libraries soon available.