Valid

Used to define a valid range or set of values that can be written. RANGES is used to set a range of values; e.g., RANGES 0,65535 defines a range of values of 0 to 65535. VALUES 1,2,3,4,5 defines valid input as the numbers 1 2 3 4 and 5. If the Valid parameter is omitted, any value can be written.