Hi Terence,
Yes, you are right. But somehow (as opposed to answers in other queries) activation of DIMP_SDUD is not required for subcon checkbox to become visible. Here's what I found comparing 2 clients and 1 IDES server:
Client 1 - DIMP release 600, hence DIMP functions not available - Subcon not visible.
Client 2 - DIMP release 606, DIMP_SDUD function activated - Subcon visible.
IDES - DIMP release 617, DIMP_SDUD function not activated - Subcon visible!
For client 1, when I choose the business function set DIMP, it pops up a message (image attached) to upgrade to release 617. So I guess just upgrading the release should solve the problem. Let me get the required approvals and confirm on this result.
I did find one supportive answer:
Thanks,
-Pratap