N-CD

From Redump Wiki

A rare feature of some Sony DADC discs (Example) built around Sony's Postscribed ID technology (Also used in LabelGate) that while technically not a form of copy protection, acts like one for Redump purposes.

Discs with n-CD can be identified by having a second data track that's exactly 600 sectors in size. Using an Asus to dump these discs will cause loads of uncorrectable C2 errors. So only Plextors can currently be used in combination with Redumper.

Another feature of n-CD and Postscribed ID is that the hashes for this second track will never match between individual discs. Exactly on how to handle verifications with these discs have yet to be decided among Redump staff.