please tell me about step by step configretion on these three topics:
1.PR Creation date of any item in PO should be =< PO creation date (check while saving the PO in ME21N/ME22N).
2.Delivery date of any line item of PO should be => the PO creation date.
3.Document date of PO should be hide.
please sir solve my these tree problam as sson as possible.