The a64l and l64a functions are used to maintain numbers stored
    in base-64 ASCII characters:

    o  a64l converts a character string to a long integer.

    o  l64a converts a long integer to a character string.

    Each character used to store a long integer represents a numeric
    value from 0 through 63. Up to six characters can be used to
    represent a long integer.

    The characters are translated as follows:

    o  A period (.)  represents 0.

    o  A slash (/)  represents 1.

    o  The numbers 0 through 9 represent 2 through 11.

    o  Uppercase letters A through Z represent 12 through 37.

    o  Lowercase letters a through z represent 38 through 63.

    The l64a function takes a long integer and returns a pointer to a
    corresponding base-64 notation of the least significant 32 bits.

    The value returned by l64a is a pointer to a thread-specific
    buffer whose contents are overwritten on subsequent calls from
    the same

    See also a64l.