A baseline is a version of a test plan tied to a particular project stage, to a release, or to an iteration. Baselines are displayed in the project plan. This makes it possible to check that test plans current for the given stage are present, and to use them for day-to-day work. You can compare arbitrary test plan baselines with each other to identify differences. Using the "Text as of Date" filter, you can obtain exactly the scenario text that corresponds to the specified date.
Create baselines of test plans before making the changes that arise from enhancements in a new product version. This lets you keep the scenario text for checking the functionality of previous versions.
If you need to make changes to several product versions at once, or to product editions partially adapted for different customers, use test documentation branching.
Baselines can be used as additional branches of test documentation, thus implementing documentation branching by analogy with source code branches. This allows documentation for several versions of the same product to be developed in parallel.
ALM automatically suggests which changes from the main documentation baseline need to be carried over into the other documentation branches.