Hi,
I have the following requirement in a B2B process.
Purchase Orders are coming from 3rd party system to ECC through IDoc (type ORDERS05) and creating Sales Order. Whenever an Orderchage is coming, I have to check whether some fields (which are maintained in a custom config table) value are changed. If yes, I have to stop processing of this IDoc and stage it for review. (IDoc's will be picked up for review through another program). eg: VBAP-Qty field may be maintained in the custom table, so I have to check the Qty in the Purchase Order change IDoc. I am facing issue here to compare the fields becuase the fields in Purchase Order and Sales Order are different. Could anyone please let me know how to achieve this??? 
I cannot do this comparison inside standard inbound function module IDOC_INPUT_ORDCHG becuase I need this as a re-usable function.
Thanks in advance