-(Digital Audio PCM): Wave (.WAV), Audio Interchange File (.AIF), Sound designer II (.SD2) and QuickTime (.MOV)
(Other formats can also be converted) -Stereo or mono pair left and right (Split Stereo). Split surround formats.

-Any Sampling Rate (44.1, 48. 88.2, 96, 176.4 and 196 kHz) & BitDepth (16, 24 and 32 bits)

Preferred Format 44.1kHz o 88.2kHz & 24 bit or 32bit.
(Even if your mix session is at 16 bit, a 24 bit final render or bounce can be done with great results)

-DDP Fileset. Even if the Disc Description Protocol is already a master it is possible to add or alter as needed.

-Mastering often requires mix adjustments and the easiest way to make them with minimal modification and files is by using stems or submixes, which are less than 8 stereo tracks with the song's main discrete elements with their respective effect processors. When stems are mixed together at 0db VU result in the final mix. Important discrete stems are bass, main vocal, and drums. Background vocals, guitars, keyboards, percussion and others can be mixed together on a single stem but it all depends on the particular arrangement of the song.

-Files from open mix sessions

More than 8 stems is mix territory. If needed, files from open mix sessions are accepted from ProTools, Cubase, Logic, OMF & Digital Performer, in which case mix levels will be adjusted and rendered in a convenient format.

How to prepare Stems for mastering:

The point is to make several stereo tracks that start at the same place so they synchronize and that these tracks contain sub-mixes by different groups of instruments and vocals with their respective effects. Most useful would be Main vocal, Bass, Drums, and another with the rest of instruments. Optionally Chorus, Guitars, Keys, Percussion. On your console MUTE every channel that is not required and bounce from the stereo buss like on the original mix without modifying any level. Do not use the solo buttons or track export functions and make sure all the bounces are stereo and from the exact same selected region or at least from the same start point.
To check the stems: Placing them on different tracks and playing them synchronized from the same start point and at the same level, their mix should sound exactly like the original mix of all the individual tracks and at the same volume.