Parameter lists that the user passes can be located in the user's primary address space or any other address space except the user's secondary address space. An ALET must qualify any address that the user passes to the PC routine (An ALET identifies the address space that contains the passed address). An address passed in a general register must be qualified by an ALET in the AR that corresponds to the general register. If you are passing ALETs, you should be aware of the rules for passing ALETs, and how to check the validity of passed ALETs. For further information on passing ALETs, see Special ALET Values at a Space Switch, Rules for passing ALETs, and Checking the authority of callers.

The user must not use ARs to pass anything except ALETs. For information on using ALETs, see Using access registers.

All addresses passed by the user's program must reside in the user's primary address space. IBM® recommends that those addresses be ALET qualified. The value of the ALET must be 0.