Many thanks @reamon for the detailed explanation. Much appreciated.
I now understand that there is no such thing as ‘custom EDI’ document. It is only a subset of the EDI Standard document.
Have another question regarding the sub versions of the EDI Standard documents.
In the scenarios where a company needs to maintain atleast two different versions of the same EDI standard document (example: EANCOM 01B INVOICE to support B2B business for two different divisions in the same company), how do we install these sub versions in webMethods and maintain to co-exist in parallel ?