A quoted character string literal is a string of printable
    characters enclosed in single quotation marks. The maximum length
    of a character string is 1,024 octets. An unqualified character
    string must contain characters only from the literal character
    set of that session.

    The printable ASCII characters consist of:

    o  Uppercase alphabetic characters:

       A-Z

    o  Lowercase alphabetic characters:

       a-z

    o  Numerals:

       0-9

    o  Special characters:

       ! @ # $ % ^ & * ( ) - _ = + ` ~

       [ ] { } ; : " \ | / ? > < . ,

    For a list of the printable characters for MCS, see the OpenVMS
    documentation; for a list of printable characters for the other
    supported character sets, see the standard for that character
    set.