SAP SD Integration with SAP Revenue Accounting and Reporting (RAR)

• SAP RAR engine has provided three default Revenue Item classes (RAI) one each for Order, Delivery and Invoice documents.
•  RAI Class contains interface program and data base tables ​ and RAI data base tables hold the raw, processable or processed data from source systems​.
• Class Type relates RAI Class to Interface Component​
• Custom Revenue item class are used either for conversion or data flow from external systems (Non-SAP) when integrating with SAP RAR for its revenue recognition purposes and Generate and Activate RAI Class for any non-SAP Systems.
• These item classes act as interface points and help the data flow from ECC to SAP RAR alongside some other essential configuration.
• Interface Component contains data structures, interface programs and possible program enhancements

Note: Source from SAP Help