Where is the Aspect Ratio transmitted in the MPEG/TS stream?

Question

Video

Hello! Something wondered and can not find the answer. How (where) is information about the aspect ratio of the screen (Aspect Ratio) transmitted in the transport stream?
I know how it is done in the original (before compression) video - in service lines. But after all, only the active part of the frame is transmitted to MPEG, the entire service is cut off (or not?), and everything that needs to be transmitted in tables / fields / somewhere else ...
Logically, this should be in an elementary stream ( not only video goes there, but also data), or in PMT. I looked at the description of PMT which I found, but I didn’t see anything like that there. And I did not find a description of the ES structure.

In general, who knows! Help, good people, do not let perish in ignorance! :)