The hexadecimal form is specified to be 14 digits grouped together and applies whether all digits are in the decimal range or whether some are in the range 'A'–'F'. In the first case, all digits are in the range '0'–'9', the check-digit is calculated using the normal base 10 Luhn algorithm, but if at least one digit is in the range 'A'–'F' this check digit algorithm uses base 16 arithmetic. The check-digit is never transmitted or stored. It is intended to detect most (but not all) input errors, it is not intended to be a checksum or CRC to detect transmission errors. Consequently, it may be printed on phones or their packaging in case of manual entry of an MEID (e.g. because there is no bar code or the bar code is unreadable).