Google App Engine version numbers?

Question

How do App Engine version numbers work? Are they only integers? Can I use floats? Can I reuse old version numbers?

Answer 1

From the manual:

http://code.google.com/appengine/docs/python/config/appconfig.html#Required_Elements

A version specifier for the application code. App Engine retains a copy of your application for each version used. An administrator can change which major version of the application is default using Administration Console, and can test non-default versions before making them default. The version specifier can contain letters, digits, and hyphens.

Each version of an application retains its own copy of app.yaml. When an application is uploaded, the version mentioned in the app.yaml file being uploaded is the version that gets created or replaced by the upload.