ORA-30205 in utl_encode.mimeheader_decode

Hello out there,

I'm trying to use utl_encode.mimeheader_decode to decode email headers but it gives me ORA-30205.
When I do the following:

select utl_encode.mimeheader_decode('=?ISO-8859-1?B?T3JkZXIg=?=') from dual;

I get:

select utl_encode.mimeheader_decode('=?ISO-8859-1?B?T3JkZXIg=?=') from dual

       *

ERROR at line 1:

ORA-30205: invalid Character set
ORA-06512: at "SYS.UTL_ENCODE", line 218
ORA-06512: at "SYS.UTL_ENCODE", line 323

Obviously Oracle does not recognize ISO-8859-1 as valid characterset. But this is the way the examples in the docs are.

Wenn I do:

select utl_encode.mimeheader_decode('=?WE8ISO8859P1?B?T3JkZXIg=?=') from dual;

I get the desired result:

Order

So the question is: How do I get Oracle to recognize the characters set the way they are used in emails?

I use Oracle 10.1.0.2.0 on Solaris 9.

Many thanks in advance,
Lothar

-- 
Lothar Armbrüster       | la_at_oktagramm.de
Hauptstr. 26            | la_at_heptagramm.de
D-65346 Eltville        | lothar.armbruester_at_t-online.de