Hello Team,
Need expert opinion on below issues.
When Storage exclusion Indicator is set in MM02-MRP4 view & storage location ATP check is active, ATP check in ECC and APO are behaving different.
In ECC, When you check this indicator - stock in the storage location is excluded from MRP and ATP check. When (no storage location is specified in sales order) in ECC. When you specify storage location in sales order, stock in storage location is considered to give confirmation. Same does not happen in case of GATP check.
GATP does not exclude the storage location stock for the indicator set, automatically, We need to implement user exit for excluding stock from GATP by deleting in CIF or changing the ATP category.
1798831 - Global ATP considers storage locations excluded from MRP
I have created ZC category for such stocks and it is not part of scope of check. When excluded storage location is not mentioned, it works fine, when excluded storage location is mentioned in sales order, it does not give confirmation. As all stock has been moved to ZC category which is not part of scope of check.
Ex :
MAT1 - in Plant P1-SL1 = 5
in Plant P1-SL2 = 10
in Plant P1-SL3 = 8 - Indicator set
in ECC
Sales ord - MAT1 PL1 = Confirmation is for 15
Sales ord - MAT1 PL1 - SL1 = Confirmation is for 5
Sales ord - MAT1 PL1 - SL3 = Confirmation is for 8
in APO-GATP
Sales ord - MAT1 PL1 = Confirmation is for 15
Sales ord - MAT1 PL1 - SL1 = Confirmation is for 5
Sales ord - MAT1 PL1 - SL3 = Confirmation is for 0 ( that is the difference)
All ideas are welcome to get similar results!! 
Regards,
Dinesh Goyal