A test suite procedure is an empty ABL procedure. It contains a list of test classes, test suite classes, test procedures, and test suite procedures. When you run a test suite, all the test procedures and test suite are also run by default.
The test suite procedure is identified as a test suite by the @TestSuite annotation and you can add the test procedures to this test suite as comma separated values to the classes or procedures attribute, similar to test suite class.
If @TestSuite annotation is present, only the classes and procedures attribute values are read for identifying the test cases to run and the business logic, if any, in the procedure is ignored.