A. When a purchase order is posted, but no invoice has been received
B. When an invoice is posted, but no relevant purchase order is available
C. When a purchase order is posted, but no goods receipt has been received
D. When an invoice is posted, but no goods receipt has been received
Explanation:
Reference: https://help.sap.com/viewer/0fa84c9d9c634132b7c4abb9ffdd8f06/2111.501/en-US/17f3a45189524e78b4a80bf51ff2b741.html