"

I'm asking for proof that it was used as an ""umbrella term for Serbs"". 

Since beside Vlah, it says ""Words[1] and phrases are pejorative if they imply contempt or disapproval. The adjective pejorative is synonymous with derogatory, derisive, dyslogistic, and contemptuous. When used as an adjective, pejorative has two meanings: (1) tending to make or become worse, and (2) tending to disparage or belittle.[2] When used as a noun, pejorative means ""a belittling or disparaging word or expression"".[3]""

THUS, I'm asking for you to prove your claims that it was an umbrella term."