invalid digit in hexadecimal number: number_value
    Facility: DEBUG, VMS Debugger
    Explanation: A numeric value other than in the range '0' through
    '9' or an alphabetic value other than in the range 'A' through
    'F' was found in a hexadecimal number. Hexadecimal numbers must
    also start with a numeric character, for example '0F'.
    User Action: Enter hexadecimal numbers specifying only digits '0'
    through '9' and alphabetic values 'A' through 'F'.