u16s -- unit type defining features related to u16 but not requiring aninstance
redefines wrappingIntegers.max:
redefines wrappingIntegers.min:
redefines numerics.name:name of this numeric type, e.g., "u64"
redefines numerics.one:identity element for 'infix *'
redefines numerics.zero:identity element for 'infix +'