In cross-memory mode, IRRACX02 gets control before compression of an ACEE if ACEEIEP is nonzero. The compression function chooses which data (if any) is to be compressed with the ACEE, based on what IRRACX02 returns:

• If IRRACX02 returns no range table and if ACEEIEP is still nonzero, RACF® assumes that it points to a standard ACEEIEP data area and compresses that data along with the ACEE.
• If IRRACX02 returns a range table, the compression function ignores the contents of the ACEEIEP field and compresses only the data indicated by the range table. IRRACX02 returns a range table by setting a pointer to it at offset X'8' into the exit parameter list.