You will hear DJs refer to a "dub plate" or "dub" in their tracklists. It is a small but important piece of DnB vocabulary.

Origin

Historically: a one-off vinyl cut, made for a single DJ to play, never commercially released. Cost real money to produce, gave the DJ exclusive access to a track for a window of time.

Today

Almost always digital. An unreleased track the producer sent to a specific DJ for promotional use. The exclusivity creates DJ-set value: you hear something at a SELECTA night that you cannot find anywhere else for weeks or months. The cultural function is the same as the original vinyl version.