Recently we had a requirement in Transaction WA08 to filter the Allocation tables based on Allocation Table type.As per standard screen selection it is not possible to filter Allocation table wise when executed the transaction.The existing User exits does not have any screen exits.
Following BADi : WFRM_X_OTB_DETERMINE_E which will allow the selection of option buttons for classic PO creation in the transaction WA08 and this can't be used for 'General Criteria' sub-screen enhancement.
The below Enhancement spots are available but it's are useful to enhance only "Vendor Purchase Order" sub-screen, and not in General criteria Screen.
Enhancement Techniques:
(a) Spot ES_RWWGENFB
(b) Spot ES_GENFBSEL
After Enhancement Allocation Table type selection field appeared in Vendor Purchase Order Selection Screen.
Hope this information helpful to others.