A white label record can be issued deliberately by a legitimate company (as in a promotional recording), but they are mostly used in such a way as to "test release" recordings of unlicensed material, thus being a potential infringement of copyright (though such usage is generally well tolerated in the industry today, with record companies and publishers having accepted that this phase is necessarry to justify the licensing of material by guaging its potential sales in dance markets). White labels are often totally legal and simply used to creat a "buzz" as well.  There is an evolving set of practices on the matter and the industry itself has never taken a firm stance in either direction, choosing to selectively enforce cases of extreme abuse. Reportedly, Todd Terry's sampling of the Thompson Twins was allowed by their publisher under the condition that he didn't "let it go gold" (sell more than 100,000 copies).  There are many derivations of this usage and it should not be merged with anything.  I have noticed that a lot of matters relating to dance music and its culture are being hastily labelled as stubs here.  The matter needs time so that sources can be gathered and readers with specialized knowledge can weigh in.  Bear in mind that many of us simpley know these things from more than twenty years experience listening, dancing , buying records and hungrily absorbing all printed publications about the matter.  This makes sourcing incredibly difficult for us, but we are sure of our knowledge (though prone as any human to a slip here and there).