Understanding the Diagnostic Subsystem for AIX

The Diagnostics Test Units Application interface consists of adapting all read functions as follows:

All data reads for the adapter must be verified that the data read is other than all 1s, unless otherwise expected. Any data reads that result in all 1s produce a unique error, which is reported to the Diagnostics application.
A test unit that expects all 1s as normal operation, because of a particular test's nature, does not report the error until that error is verified by the requesting data as being caused by all 1s.
Diagnostics application developers and test unit developers must determine jointly a unique error code for enhanced error handling.