One of a closed set of NUMERIC values — a sample-rate menu, a quantum ladder.
REFUSES a number outside the set rather than clamping to the nearest member: the members are
discrete choices, not a travel, and "the closest rate to the one you typed" is a different
decision from the one the caller made. The refusal names the legal set so a client can render
the menu it should have offered.
One of a closed set of NUMERIC values — a sample-rate menu, a quantum ladder.
REFUSES a number outside the set rather than clamping to the nearest member: the members are discrete choices, not a travel, and "the closest rate to the one you typed" is a different decision from the one the caller made. The refusal names the legal set so a client can render the menu it should have offered.