Do you want to say:
Version 1 = 25GB Single layer disc.
Version 2 = 25GB x2 Double layer disc.
Version 3 = 20GB~ x3 Triple layer disc.
Version 4 = 20-30GB~ x4 Quadruple layer disc. ????
Do not forget that version 1 of BD-RE was not computer compatible, so version 2 and later are for computer use. The same happens with BD-R, it has 3 versions, all for pc. So, will I be right if I say:
Version 2 = single layer disc
Version 3 = dual layer disc
Version 4 = multi-layered disc
Version 1 = single layer disc
Version 2 = dual layer disc
Version 3 = multi-layered disc ???????????????
For BD-RE version 4 and BD-R version 3 things are easy, we have multi-layered discs (XL), as wikipedia mentions. But what is going on with BD-RE version 2 and 3 and BD-R version 1 and 2;