Caro Kann Exchange: what pawn structure(s) am I looking at?

I was (am) learning from chapter 1 of Soltis' book "Pawn Structure Chess". Chapter 1 is about the Caro Kann Structure. But not the Exchange "structure" as it doesn't lead to the usual d-vs-e pawn trade which was initiated by black - resulting in sort of a triangle for black.

Both Soltis' book nor Rios' book seem to cover the pawn. Early on white misses the e-pawn and black misses the c-pawn. What pawn structures must I learn to know the needs of such a position?

This is the approach - pawn structures and its needs in the opening - I want to use as the "regular" Caro Kann study was very illuminating.

This is one of the most-studied structures in chess, the Carlsbad structure. Whole books have been written about this. The Caro Exchange version has colors reversed compared to the most common occurrence of the structure, which is in the Queen's Gambit Declined, but it can come up in a bunch of different openings.

Yes, I suddenly realized just when I finished making this post. It's in Soltis' book, the chapter on the "Orthodox Carlsbad". Thanks nevertheless. it confirms this is the right track.

In my mind I simply forgot to check for reversed colors.

White should respond with 4, Nf3 or 4, Nc3

Neither of them actually. 4.Bd3 is the main move by a long shot, with 4.Bf4 a distant second.

Alien gambit

Ok