I just learned that SEU stands for service entrance unarmored (as opposed to armored service entrance, and USE was already taken). Does SER stand for service entrance round?

Yes it is round but useally have either 3 or 4 conductor [ the SER is common with 4 conductor duex hot's and one netural and one bare conductors ]

Merci , Marc

We always call it 'riser' cable. (Service Entrance Riser) Explanation was with the insulated neutral & bare ground, it's used after the first means of disconnect.

John