hello! what does "that" refer to in this sentence?
"In fact, some features that were at one time available on only mainframes have been adopted..."
Sorry folks, that'that' isn't a subordinating conjunction; it would be in a context like 'He said that they were at one time available...'. In the context given in the OP, it is, as bhai said, a relative pronoun. There should be the tag :mea-maxima-culpa: