Specifies the character set used for object names such as cursor
    names and table names. If you do not specify a character set in
    this clause or in the NAMES ARE clause, the default is DEC_MCS.
    This clause overrides the character set specified in the NAMES
    ARE clause.

    The specified character set must contain ASCII.

                                   NOTE

       If the dialect or character sets are not specified in the
       module header, SQL uses the RDB$CHARACTER_SET logical name
       to determine the character sets to be used by the database.
       See the Oracle Rdb SQL Reference Manual for more detail
       regarding the RDB$CHARACTER_SET logical name.

       The RDB$CHARACTER_SET logical name is deprecated and will
       not be supported in a future release.