The ISO Latin-1 Multinational character set is a superset
    of the traditional ASCII character set used by versions of
    OpenVMS previous to 7.2. With extended file specifications, all
    characters from the 8-bit ISO Latin-1 Multinational character set
    are valid in file specifications, except the following:

       C0 control codes (0x00 to 0x1F inclusive)
       Double quotation marks (")
       Asterisk (*)
       Backslash (\)
       Colon (:)
       Left angle bracket (<)
       Right angle bracket (>)
       Slash (/)
       Question mark (?)
       Vertical bar (|)

    File specifications on an ODS-5 volume can also include Unicode
    (UCS-2) characters. Because each Unicode character requires
    two bytes, the use of Unicode characters can affect the maximum
    permitted lengths of file specifications.