Hi Jitendra,
As you said, I can append the strucuter for those custom fields;
The link that you provided will not be useful in my case.
A custom IDOC type is already developed with the output types and procedures , to trigger the IDOC whenever the SO is created/changed, so i need to work with the same Extended IDOC type.And also i have searched for the message type for any additional configuration, but the existing development is purely done with the message control only.
as you said how can i see those fields in the USER-EXIT if i append the structure to the standard table.
Regards,
Sumanth.P