I'm working on version 2 of an existing book. I'm checking in this new version as a separate, distinct content spec, so now we have two content specs with different IDs, different version numbers, but the same name. When I check out either of these content specs, it attempts to create the same project directory. So, perhaps it's best to construct the project directory name using both the title and the version of the content specification, so that I can check out both versions of the book at the same time, and be clear about which is which. I can think of two possiblities: <title>-<version> or <title>/<version>/
I believe the <title>/<version> approach is the better way to handle this because that way it provides a very clear hierarchy of different content specifications and their different versions.