Oracle Rdb supports the use of the UNSPECIFIED character set.
    You can make comparisons and assignments between text objects
    (columns, literals, and so on) that have the UNSPECIFIED
    character set, and any other text object regardless of the
    character set of the other text object.

    The characteristics of the UNSPECIFIED character set are as
    follows:

    o  The character set ID is 32767.

    o  It can be used to specify any session or database character
       set, including the identifier character set.

    o  It is a single-octet character set (fixed).

    o  It applies casing (uppercase and lowercase) only to ASCII
       characters.

    o  It contains ASCII, as follows:

       -  The space character is the ASCII space character (0x20).

       -  The wildcard character is the ASCII underscore (0x5f).

       -  The string wildcard is the ASCII percent (0x25).