Action Box Function Module In Notification

Hi,

I want some information on function module assigned to Action Box. If you go in F2 type notification then in (spro) function 0002 (Assign purchasing Document) and also in 0005 you can see there is function module assigned to it.

And there is two function module in each function like 0002 and 0005.

1) Under Function tab - Function Module

2) Specific details for task - FM when saving

So why there is two Function Module. What is the use of it.

I want some customized action so for that what necessary steps should I considered. So how will I customize this process. And my technical consultant create two or one function module

Regards,

Saurabh Kumar