Compatible enhancements are interface enhancements that change the BAPI without effecting the downward compatibility of the BAPI. Applications which access the BAPI are not affected by compatible enhancements.

Compatible enhancements are:

• New optional parameters
  A parameter is considered to be optional if it does not have to be included in a BAPI call.
  A new optional parameter can be added in any place in the interface.

• New optional fields in structures
  A field is considered to be optional if it can be left out completely in a BAPI call.
  The fields must be added to the end of a structure. This is because the function module upon which the BAPI is based is called via RFC. It does not matter how the fields are arranged in a structure or table because the whole structure is always forwarded. It is not first broken up into fields.

Compatible Changes to Function Modules
In interface	New optional parameter as a field
	New optional parameter as a structure
	New optional parameter as a table
	Adding new optional field to the structure
	Adding new optional field to the table
	Compatible changes to field types (in the ABAP Dictionary)
	Converting mandatory fields to optional fields
In program code	New additional coding that does not involve changes to the interpretation/processing logic
	Changes to the existing code which do not involve changing the interpretation or processing logic
	Using customer exits

When making changes, be sure to follow the guidelines in the BAPI Programming Guide.