If the calling program is in AR mode, all addresses that it passes, whether they are in a GPR or in a parameter list, must be ALET-qualified. A parameter list can be in an address space other than the calling program's primary address space or in a data space, but it cannot be in the calling program's secondary address space.
Figure 1 shows one way to format addresses and ALETs
in a parameter list. The addresses passed to the called program are
at the beginning of the list and their associated ALETs follow the
addresses. Notice that the third address has the high order bit set
on to indicate the end of the list. For an AMODE 64 program, instead,
the parameter list consists of 8-byte wide address slots (still followed
by 4-byte wide ALET slots) and the high order bit of the last address
slot would not be used to indicate the end of the list.
Figure 1. AR
Mode Parameter List When Not AMODE 64
All addresses that an AR mode target program returns to an AR mode caller, whether the address is in GPR 0 or 1 or in a parameter list, must be ALET-qualified.