The character set HEX is comprised of two octet hexadecimal
    characters '00' through 'FF' and has the characteristic that
    the contents of data objects with this character set will not
    be automatically translated to the display character set when
    automatic translation has been enabled.

    It may be used in conjunction with the CAST and TRANSLATE
    functions to obtain the hexadecimal equivalence of text objects.

    Translation to the HEX character set will translate source data
    octet by octet into hexadecimal notation.

    Translation from the HEX character set will translate from
    hexadecimal notation to the destination character set.

    For example:

    SQL> show character sets
    Default character set is DOS_LATINUS
    National character set is DOS_LATINUS
    Identifier character set is DOS_LATINUS
    Literal character set is DOS_LATINUS
    Display character set is DOS_LATINUS

    Alias RDB$DBHANDLE:
     Identifier character set is DEC_MCS
     Default character set is DEC_MCS
     National character set is DEC_MCS
    SQL> show automatic translation
    Automatic translation: ON
    SQL> create tab latin (f1 char(4) char set win_latin1,
    cont> f2 char(4) char set dos_latinus);
    SQL> insert into latin value ('AÉÖ','AÉÖ');
    1 row inserted
    SQL> select f1, cast(f1 as char(8) char set hex),
    cont> f2, cast(f2 as char(8) char set hex) from latin;
     F1     F2
     AÉÖ 41C9D620   AÉÖ   41909920
    1 row selected
    SQL> select cast (_hex'9099' as char(2) ) from rdb$database;

    1 row selected
    SQL> select translate (_hex'9099' using rdb$dos_latinus )
    Cont> from rdb$database;

    1 row selected

    The previous example also shows automatic translations between
    the literals character set DOS_LATINUS and the field F2
    containing WIN_LATIN1, and the subsequent automatic translation
    from the F2 field back to the display character set.

    The hexadecimal display of the field contents shows that the
    actual data stored in the database is different for field f1
    and f2 even though the input literals and the output displayed
    appears identical.