A related data set is a subset of a data set. Create a related data set that contains specific data from another data set. For example, you create a data set DA_APP when you test version 1.0 of an application for a specific customer. You test specific features of the application in this release. The data set DA_APP contains tables relevant to the tests you run. When you test the next hotfix version of the application, you test a few of the features and you require some of the data in the data set.