Trigger special function output type through a custom program

Hi,

I have to trigger the special function output type from a custom program.

This custom program contains a BAPI and the output parameters of this BAPI are required as input to the second BAPI which is contained in the form routine of the special function output type.

I am not able to understand how to trigger the special function as I dont know how the nast-objky will be updated

and how the BAPI parameters will be passed.

Is this has to be done through a Idoc

Can anyone guide me on how to handle the above functionality.