POV 3rd Person Limited

If you are writing in 3rd person limited POV, which is the expected style of writing a novel these days, (unless you're writing in 1st person, which I hate,) then everything you write must be written in a particular character's perspective. You can jump from one character to another after a scene break, but using a character's POV includes using the names of people the POV character knows.

Meaning if your POV character happens to know the names of the other characters with whom he or she is interacting, (or fighting,) then you can use those names. This came up with my current WIP, because Trent was remembering his training at the Tokyo Dojo when he was sparring against several other senseis at the dojo. At first I didn't call those other senseis by name. I was using "his opponent" or "his foe" or "the man." But last night while rereading and revising, I realized, wait a minute. Trent had trained and worked with these guys for twenty  years. So he would know their names.

I went ahead and gave these guys names, and used them. Now against the  dozens of foes whose names he doesn't know, then they must remain nameless. And that's what 3rd person POV is about. Same thing with first person. If the POV character knows their names you use them. If he/she doesn't, then you don't. Simple as that.