[AccessD] A2003: The Changes you requested blah blah blah

Hi Guys
What is the error number that spits up when users create a duplicate
value they shouldn't have

You know the one ...
"The changes you have requested were not successful because
They would create duplicate values in the blah blah blah"

Also where do I trap this, where do I put the 
if err.number1234 routine?


Many thanks

Darren