Return from subroutine if semaphore ss is false. The semaphore base address bb is optional; if omitted it is taken to be 0.
For more details see the semaphore tutorial.
+ From dialect 16 the address argument will be jndexed when executed inside a MultiTrack task and will be indexed if the instruction is preceded by the IasJ: precode.
Dialect restriction: Available only in boards with dialect 12 or greater.