Canadian postal codes are both letters+numbers as well (formatted AxByCz, where A,B,C are letters, x,y,z are numbers), so UK seems like it would be safe. Too m

Canadian postal codes are both letters+numbers as well (formatted AxByCz, where A,B,C are letters, x,y,z are numbers), so UK seems like it would be safe. Too many or few characters, like you point out as the case for Taiwan, would be the problem.