DiscT @ 2 (for " disc tattoo " - cf Leetspeak ) is a technology developed by Yamaha to label CDs on the data page. To this end (outer edge ) is an arbitrary pattern burned into the unused portion of the CD. The " image " is created then by the contrast difference between ' marked ' and ' unmarked '.
The process basically works with all CD types, wherein an image is only visible when the contrast difference is large enough. The older CD- Rs, the very dark green ( cyanine ) or dark blue ( azo ) were worked best. The only CD -R, made today even with cyanine or azo, come by Taiyo Yuden ( Plextor, Verbatim Pastel Disc) and Mitsubishi ( Verbatim DataLifePlus ).
A glued label or classical CD printing ( in the printer ) addition was still possible.
The only drive that used this technique was the Yamaha F-1. The technique was further developed by, licensed by NEC and has come under the name Labelflash DVD burner on the market.