User exit for CJ02

Hi Experts -

I am working on a client requirement dealing with t code CJ02 in SAP PS module. Customer wants some custom checks on certain fields when creating/editing WBS structure under a project. I need this validation to happen at PAI event (ENTER or SAVE)

Is there a SAP provided exit that can be leveraged for this functionality?

Please let me know. Much thanks.

Thank you,

Amit.