Is this a reverse return system?

AlwaysLearning2024

hi everyone!

Trying to understand how my building was designed and piped.

1937 4 plex

Hydronic heat with gas fired Weil boiler that replaced an oil fired model.

Recessed Fin tube

I traced down the supply and return best I could for the first floor from the basement.

Seems like each heat exchanger has a supply and return.

I noticed possible the last supply “dead ends” near the boiler.

Is this a sign of a reverse return system?

Mad Dog_2

It's hard to tell without a drawing or seeing it in person, but basically the first Radiator off the supply is the last to return to the boiler. Mad Dog 🐕