Set field of screen mandatory WITHOUT changes on sourcecode - possible?

Hi all,

is it possible to set a field mandatory without making a modification (neither source nor screen)? I am not allowed to do this. Are there transactions in which I can put in program name, screen and fieldname to make this filed mandatory? There is no customizing available to change field behaviour. Have anyone an idea?

It is SAP ABA 620.

Thx a lot!

Regards