Double Layer vs. Dual Layer
There are currently two formats on the market that support recording to two layers of a DVD disc. The first was presented by the DVD+RW Alliance for the plus (“+”) format and given the formal name “Double Layer.” The DVD Forum followed with its own standard for the dash format (“-”), which it dubbed “Dual Layer.” For now, drives are only available in write-once formats called DVD+R DL and DVD-R DL.
According to DeMoulin, “Sony was a pioneer of dual format DVD burners that support both plus and dash standards, and the first to introduce Double Layer recorders for the PC. With the 800 series, we now also support both double and dual layer burning.”