(Corresponds to Section 4.3 of ANSI X3.9-1978 FORTRAN 77.)
An integer constant also may have one of the following forms:
B'binary-digits' O'octal-digits' Z'hexadecimal-digits' X'hexadecimal-digits'
binary-digits, octal-digits, and hexadecimal-digits are nonempty strings of characters in the set `01', `01234567', and `0123456789ABCDEFabcdef', respectively. (The value for `A' (and `a') is 10, for `B' and `b' is 11, and so on.)