Although certain fields within the PSW may be tested or set by using non-privileged instructions, testing or setting the remaining fields may only be accomplished by using privileged instructions.
Contained within the PSW are the two bit condition code, representing zero, positive, negative, overflow, and similar flags of other architectures' status registers.
Conditional branch instructions test this encoded as a four bit value, with each bit representing a test of one of the four condition code values, 23 + 22 + 21 + 20.
Its contents may be examined with the Extract PSW instruction (EPSW).
S/360 Extended PSW format only applies to the 360/67 with bit 8 of control register 6 set.