ACATS 3.0 User's Guide
4.2 Test Classes
There are six different classes of ACATS tests, reflecting
different testing requirements of language conformity testing. Each test
belongs to exactly one of the six classes, and its membership is encoded
in the test name, as explained later. The purpose and nature of each
test category is explained below. The test classifications provide an
initial indication of the criteria that are used to determine whether
a test has been passed or failed.