Marking on 90 mm

This belongs to 90 mm high explosive anti tank tracer projectile.
The top of projectile three times “T” Letter stamped.
So I want to know why these letters stamped on projectile?

Thanks alot.

I believe the “Ts” indicate Tracer–perhaps because they are in red ink, you could expect a red trace. We know, of course, that it is a tracer round, due to the “HEAT-T” nomenclature.
Hope this helps–at least till one of the “experts” weighs in…

But if those indicate tracer, why three times?

Yes.I got it.
Thanks your helping.