To my understanding, relative pronouns and relative adverbs, in relative clauses, serve a similar function to subordinating conjunctions in other types of clauses. According to my "Grammar for English Language Teachers" book by Martin Parrott, in the sentence "Is this the room where the murder happend?" 'where' acts as a relative pronoun (and some people would call it a relative adverb). (p. 354) In a different section of the book (p. 423) subordinating conjunctions are discussed says that 'where' is a subordinating conjunction in the sentence "He wanted to stay where he had always lived." My question: why is it 'where' a subordinating conjunction in the second sentence, but a relative pronoun/adverb in the first sentence? Are relative pronouns/adverbs simply types of subordinating conjunctions??