My company has an ASP.NET application in a VSS repository. Management would like some of the files in the repository to be read-only to most users, while the rest of the files would be writable to all users. I don't think this can be done, but if its possible, it would require sharing.
One possible strategy would be for the entire project to be in folder that is read-only to some users and writable to the others. Then you can have another folder that is writeable to all users. Only the individual files in that all users have write access to will be shared to the folder writable by all.
The problem with this is one of convenience. Some of the files only privileged developers will have access to are base classes so the writable branch will not compile out of the box.
As far as using a SCM that allows per file ACLs, I'm open to suggestions, but I have asked that question separately.