I've always used the word branch when describing the type of industry, line of business or operation category. Please note that I'm not referring to a part of a concern structure as in "Scranton branch of Dunder Mifflin".
For instance, to express that John is in finance and doesn't understand the importance of well defined code structure, which a programmer or other IT professional definitely would, I'd state the following.
"Jonh doesn't know jack. He's not in our branch."
I've never got eye browse arousal on this so I lived happily ignorant that it might be an incorrect usage of the Swedish term (borrowed word from English) until my colleague had the cruelty to point that out for me.
I tried to defend my position with an online dictionary but apparently there's a bug in their logic because it only confirmed the said colleague's critique of my expression. :)
Seriously speaking, though, I'd like to get some light shed on the usage of the term. Is it understandable? Commonly used? Poetically or metaphorically expressed? Just plain wrong?