When adding SDTM variables that are not in the SDTMIG table for that domain, one need to follow the order as given in the corresponding SDTM MODEL. So NOT at the end.
For example, for SDTMIG 3.2, the SDTM model is 1.4, for which you can find the documentation at:
I would also encourage you to use the “CDISC Library Browser” for that (free account for CDISC members): CDISC Data Standards Browser.
Modern software such as our SDTM-ETL submission developer inserts such variables at the right position automatically.
With best regards,
Jozef Aerts
XML4Pharma and CDISC Volunteer