mandatory fields in alv table

Hi all,

Based on the PR type the mandatory fields will change in alv table.

for example: if PR type = z1, the material no and plant is mandatory, account category and item category is optional

but PR type = z11 , the material no is optional , account category and item category is mandatory.

(pr type is not included in table, input field is created for that)

so based on PR type mandatory fields are changed..

can anybody suggest how to do this in alv table.??

Thanks all,