The bad experience I have with Table API is I can't get anyone to tell me how it works. I had the impression that if I created a constraint with a corresponding error message and then installed Table API in that application, then that error message would be displayed in SQL*Plus if I violated the constraint. It doesn't and I get the feeling that I am way off track. However, the only feedback I can get is that the CG$ERRORS package must be installed, which it is.