Program Calibration Area
Space at the beginning of the CD for calibrating the laser to read or write to the CD.
The Power Calibration Area (PCA) is present only for CD-R and CD-RW media for the purpose of write power calibration. The PCA is divided into two areas: the test area and the count area. The test area is divided into 100 calibration partitions. The count area is an accounting area for recording usage of the test area.