See black dot on "OUT". Is it a junction or does it mean something else? This is the only black dot on the diagram, despite it having multiple splits and junctions elsewhere in the circuit.
So my oven just broke. The OUT connector (in grey) looked chipped, possibly from a short. This is what it look like in real life. The camera angle might not show it, but I think the connection is same as the IN below.
A different angle:
The black dot most likely represents the terminal with the black silkscreen outline on the PCB, the designers wanted people to make sure 'out' pin gets special attention and demarcation.
I've done this for service people in documentation to make sure they 'don't screw up' polarity (and sometimes they still do)
It also appears that the terminal is even a different color for this purpose .
If you didn't plug the common terminal of the heaters into 'out', it could be really bad. It probably won't matter as much if you got BA and BR swapped.
