I need a little precision about "Q Mode 5 Lead out sub channel with point D1 value". It seems that in lead out, such sub channel could exist in the lead out area. The 72 data bits should be like below : 8 bits for track number (fixed, must be AAh=Lead-out) 8 bits for point (D1h, Identifies a multi session lead-out) 24 bits : I do not know ... 8 bits: I do not know ... 24 bits : I do not know ... I assume that Mode 5 subs are present for multi session discs (that mean for me [2,N] (N>=2) sessions). I had crawled everywhere, even on ECMA and MMC but no information about it ... Thanks for all the help you could provide. Regards.