All CD’s are pressed from a digital data source, with the most common sources being low error-rate CD-Rs or files from an attached computer hard drive containing the finished data (e. g., music or computer data). Some CD pressing systems can use digital master tapes, either in Digital Audio Tape, Exabyte or Umatic formats. However such sources are suitable only for production of audio CD’s due to error detection and correction issues. If the source is not a CD, the table of contents for the CD to be pressed must also be prepared and stored on the tape or hard drive. In all cases except CD-R sources, the tape must be uploaded to a media mastering system to create the TOC (Table Of Contents) for the CD. Creatve processing of the mixed audio recordings often occurs in conventional premastering sessions. The nickname often used for this is “mastering,” but the official name, as explained in Bob Katz book, Mastering Audio, edition 1, page 18, is premastering. After all, there still has to be the creation of another disc which has the premastered audio but which supplies the surface on which the metal master will be electroformed. So, there still needs to be the grandmother disc before the master stamper can be formed atop.