10. Notes on Revert to ... and Diff Against... GUI Commands : Diff Against...

Diff Against...
In relation to the “Most Recent Version” of foo_3.java in the prod3000_itr_user1 workspace stream (prod3000_itr_user1/4), Diff Against... can used with:
Backed Version—prod3000_itr/2. For a Diff operation, this is always the current version in the backing stream.
Basis Version—prod3000_itr/1. In this example, this is the previous promoted version, and is the base version originally used to create Version 4. The basis version is the version you began your work with—usually the version from the backing stream downloaded from the server by your last update operation, or the last time you promoted the file, whichever came last.
Previous Version —prod3000_itr_user1/3. The previous kept version in the workspace stream. (Note: Diff Against... the previous version is available from the Other Version option in the Version Browser.)
Similarly, foo_3.java in the prod3000_itr_user1 workspace tree can be compared with the backed and basis versions from the prod3000_itr backing stream using the rules above, and its most recent version, prod3000_itr_user1/4 in the workspace stream. It can also be compared to the previous kept version and any prior version using Diff Against.. -> Other Version from the Version Browser.

Borland