This is from Metalink:

Note:232120.1
Subject: ORA-31600: invalid input value EMIT_SCHEMA for parameter NAME in function SET_TRANSFORM_PARAM


Change(s)
~~~~~~~~~~
One of the known causes for the error above is that a patchset was recently applied to the database but one or more of the patchset steps were not performed.
Cause
~~~~~~~
View the readme notes for the patchset recently installed. You will see a step that should have been performed that directs you to run the script named catpatch.sql. Very likely this step was never performed.

Fix
~~~~
As the sysdba user run the catpatch.sql script found in the directory named $ORACLE_HOME/rdbms/admin. Before you submit this script, view it's contents. You may see that this script places the database in restricted mode.


Thanks,

Sesha.



--------------------------------------------------------------------------------

From: Oracle, Sam Perciasepe 14-Jan-04 12:57
Subject: Re : Ora-31600 encountered during Export



Hi Richard,

As Sesha has already pointed out, you are encountering the issue as described in Note:232120.1

Article-ID:
Title: ORA-31600: invalid input value EMIT_SCHEMA for
parameter NAME in function SET_TRANSFORM_PARAM
Document-Type: PROBLEM


It appears that the Postinstall Actions were not completed after the 9.2.0.4 patch set was applied.
So the solution is:

1) Cleanly shutdown the database.
2) Connect to the database using the SYS/password as SYSDBA account.
3) Startup the database using command:

STARTUP MIGRATE <<< This starts up the database in restricted mode.

4) Run the catpatch.sql script from the $ORACLE_HOME\rdbms\admin directory.

5) Cleanly shutdown the database.
6) Startup the database with the command:

STARTUP

7) Perform another export of the database.


This should resolve the errors being encountered.

Regards,
Sam.

HOPE THIS HELPS