04-24-2018 01:30 PM
To get a more accurate and complete answer, I'd suggest asking the SDS team at CDISC.
I will take a stab at answering, but my answer doesn't feel particularly fulfilling even to me. Unlike the --STDTC variables where the -- takes on the domain id, the DM domain's Subject Reference Start Date/Time uses RF and not DM as the prefix. I can't give you a justification over the difference, but there is one. Interestingly, in the 3.1.1 STDMIG the DM RFSTDTC variable was classified as Timing as were the other --STDTC patterned domain variables like CMSTDTC.