Get click event Screen.

Hi experts.

I have been  working with determination with bopf.

My Determination is called in all modification screen.

I need it be called only when the user click in a nwbc menu option specific.

How can i know what menu is clicked by the user to put in my code?

If i need create a event to menu please send a tutorial.

I have a TM guide but i didnt find how to do it.

For example in sap ecc the abap use sy-ucomm but how to do it in bopf inside a determination?

Thanks.