Test Sample 5B.2 provides the same support but from a new stamper. Orange Book reflectivity and radial contrast tests are also supported by 5B.2, plus reference values of jitter and length deviation for all legal pit and land lengths. Philips also designed playability disc SBC 444A so that drive manufacturers can stress their pickup and servo designs. This disc contains three types of defects of various durations that disrupt radial, focus, and spindle servo circuits, thereby either creating or lengthening errors related to these defects. Disc SBC 444A contains three types of intentional defects having predictable and reproducible properties.
Interruptions are the first type, and are recorded imperfections that simulate scratches.
Good drives should be able to correct errors arising from these regions. These interruptions may generate uncorrectable errors in drives with poor pickups or servos. Proper servo and pickup designs are confirmed by a small number of errors. The third defect type is a large, simulated fingerprint that should not generate uncorrectable errors. Philips disc SBC 444A can be used as an error reference disc.