Each executable file in the project can have an optional baseline coverage file associated with it. This file is normally used when comparing coverage results from different test runs to determine how specific tests affect code coverage.
To make use of the baseline coverage file, copy the coverage results of an initial set of tests into a separate file (e.g., use the Save Coverage As command). This copy will be the baseline. Set the name of the baseline coverage file in the Properties for the executable file, or use the Load Baseline From command.
Then run additional coverage tests without clearing the previous results (do not use the Clear Coverage command). To determine what new code was executed by the added tests, use the Diff Baseline command. This step may be repeated as often as desired using the Load Baseline command to return to the initial test coverage file.