Program Order

See https://stackoverflow.com/questions/26933991/what-does-actually-program-order-mean

the result of any execution is the same as if the operations of
all the processors were executed in some sequential order, and the
operations of each individual processor appear in this sequence in
the order specified by its program.

For ?SV this also includes the Sub-execution loops, VL and SUBVL. Each of these must have their "Program Order" preserved.