This is a bit confusing
ISRO showed this concept for the AB-TSTO:-
I had intially thought it would be a DMRJ, but here they show ramjet and scramjet are separate. Feels like the turboramjet alone would be similar to the SR-71's engine. And then you add a separate scramjet and two separate rocket stages on top of that. Quite a complex vehicle. Basically, its 5 stage: turbojet -> Ramjet -> Scramjet -> Rocket stage 1 -> Rocket stage 2.
SR-71 had this:-
Overall, I don't understand why they aren't keeping the turbojet separate and then diverting airflow to a DMRJ for both ramjet and scramjet flight? That seems way more simple compared to the turboramjet.
For an SR-72 style aircraft, we just need to replace the rocket stages with fuel tanks for the scramjet.