Vinyl mastering is a form of analog mastering whereby the album is prepared for optimal playback on a vinyl record. A mastered song for a CD and digital release is quite different from the same song that is mastered for vinyl. The overall equalization and balance is similar but dynamic range and optimization can be quite different. See RIAA Equalization.
Vinyl mastering is an additional cost of $20 per song. The files are delivered as .WAV or .AIFF, whichever the cutting plant requires. In some cases DDP files are required.