In order to check and guarantee the quality of the transferred digital data, a complete Master Tape is tested in a special work session to see how often the automatic error correction turns itself on. The number of CRCs (drop-outs, tiny "recording holes") serve as a standard for measuring the quality of the tape material employed. Since the master tape has a continuous time code, all the levels of Error Correction can be chosen with absolute time precision and represented in the appropriate form.
A master tape is in perfect condition and ready for the CD production only when the CRC rate is so low that the data can be read without a loss.
[The way to the Classical-CD]