SET EXPLAIN ON

Hello, in SQL and 4GL the SET EXPLAIN ON statement may be used to obtain a measure of the work involved in performing a query. Unfortunately this statement in our implementation is leading to the error code 581, which says that there in an error in loading a message file, which in turn seems to point at an unsufficient implementation. Now my questions to the audience: 1. Where should the message file be located? (my guess: $INFORMIXDIR/msg) 2. What should the name of the message file be? Thanks for reading this posting. H. Stemper