Validation for a selection screen used as a subscreen

Question

Hi friends,
I have a screen say '0001' in that screen i have three subscreens 0002 0003 0004
In the subscreen 0002, i have declared three selection screens 0102, 0202, 0302
In the Application toolbar of the screen 0001 (PF Status) i have declared three push buttons A, B, C,
On click of A i ll invoke 0102 selection screen inside the subscreen 0002.
Similarly On click of B i ll invoke 0202 selection screen inside the subscreen 0002
Similarly On click of C i ll invoke 0302 selection screen inside the subscreen 0002.
I have completed till the above ...
My problem is ........................
The selection screens will have their own Parameters and select options .....
some of them are mandatory & some of them not .......
Now when i switch from one push button to another say from A to B and then again to C .... for each and every click it is asking to fill in the mandatory paramters and select options ........ and then only allowing to move to the next sel screen .......
Needed solution:
~~~~~~~~~~~~~
1. How can i avoid this message "Fill in the required fields" ?
2. How can i validate the user entries if i take away all the "OBLIGATORY"
    additions in the selection screen declaration part
3. Where can i write "At selection screen" validation? becoz iam using a function
    group for the creation of screens and all and have included the selection
    screen declaration in the top include of the Function group?
Hope iam clear with my question!!
Revert back if you need more clarrifications on the question itself
Cheers
Kripa Rangachari .....

Answer 1

Hi,
   In the pf status - for push buttons give the type as E.
Write the processing for this in at exit command.
Validation should be done in AT SELECTION-SCREEN ON field.
Reward if helpful.