ComplexMap Riddle

Im usually pretty good at ComplexMaps and implemented a couple, but I have one that is stumping me on how I can implement it.  My problem is I have no real "leading data" to key off of and need something else...

It goes a little bit like this:

D123456     THING1   THING2    THING3   THING4

D789101     THING1   THING2    THING3   THING4

T    THINGX    THINGZ

In looking at the above, I need two record maps, one for the "D" rows (repeating) , and one for the "T" row, which is basically the trailer.  Additionally the spaces between the records are a reality too.

The issue is that when I set the trailing data to "D" it is actually part of the real data, and no longer accessible, so in both cases I have no real trailing data to use because I need those values persisted in the record maps.

Ive seen some examples where folks inject a blank record as the leading data, but have no real idea how that works or how to implement it.

Any ideas ?