The discussion that follows presumes that any file copying necessary to produce test data was performed under adequate controls to preserve data integrity. Furthermore, the tests described are applicable to both mainframe and PC environments. The focus of this material is on explaining the logic underlying various substantive tests and on illustrating the functionality of ACL in achieving audit objectives. The audit procedures described are based on the file structure in Figure 10.7. These structures indicate the key data and logical linkages between files. A description of each file follows.