Enhancement Points in IW31

Hello,

We would like to insert a user exit in transaction IW31 --> Operations tab.

Scenario: when PM02/PM03 is chosen as the Control Key, a dialog box will appear for the "External Processing Operation". From there, we could enter the Material Group. This is where we want to insert the user exit. When users enter a code, the system will propose a more correct code.

Please advise on where to place the user exit.

Let me know if you need further clarification.

Thank you very much in advance!

M