How to know if the user is in change or display mode

Hello!

I created a user exit macro for my planning book. if the user is in display mode, i don't want him to be able to run the macro. He should only run the macro in change mode.

How to determine in an user exit macro (i.e in an abap programm) if the user is in change or display mode?

There is the FM /SAPAPO/DATA_IS_LOCKED with this parameters but it doesn't work.

Thanks in advance,