Hi,
Why and what is the prupose to use RSO2?
RSO2 - used to create a custom data source.
Assuming as your data source is standard one.
To enhance data source you need to know the extract structure name.
Extract structuer name you will egt thru RSA6--> double click on data source and see there.
Other wise at RSA6, select data source and click on enhance data source.
Later add logic at CMOD, under master data exit.
Thanks