A workspace can be based on a snapshot, instead of a stream. Initially, this might not seem to make sense; after all, a snapshot is an unchanging software configuration, and a workspace is a tool for getting changes in and out of the data repository, but a snapshot-based workspace is quite useful — for example, for performing maintenance work on a previous product release.
When you create a snapshot-based workspace, AccuRev copies the versions in the snapshot to the new workspace tree. (This step is just like the creation of a stream-based workspace.) It doesn’t make sense to
update the workspace, because there’s guaranteed to be nothing new in the snapshot. It’s a configuration that never changes.
You can make changes to the files in a snapshot-based workspace, saving the changes in the workspace stream with the keep command. You can’t
promote the changes to the snapshot, though, because the snapshot is a configuration that never changes.