I take several heart meds,none of which are "scheduled",and am routinely told (in MA) that the prescriptions are good for a year after it's written.
Well the consensus of 4 Pharamcists (one who just took his law exam) is that its a 1 year RX. Although, they did hesitate...hahah!
It's probably buried in what is euphemistically referred to as "administrative law".