Can you be a bit more specific about which parts of the CMIS spec you are referring to ?
For example, CMIS 1.1 states about the AtomPub service document:
The service document will also be available from Atom Entry and Atom Feed documents via a link relationship
service. That AtomPub service document MUST then only contain one workspace element which
MUST be the workspace representing the repository containing the Atom Entry or Atom Feed document.
So it 's pretty explicit about the existence of only 1 workspace.
In general, ModeShape's CMIS support is entirely built on Apache OpenCMIS. So if the latter supports multiple workspaces, so does ModeShape. But I don't see anything about multiple workspaces in the CMIS spec...
I also found resources referring to this section of the specification. In my research I couldn't find anything about multiple workspace support either in CMIS, so I am inclined to believe that there is no support either. I looking for confirmation about this from you. Thanks Horia.