3) If you go double-layer, you’ll have to start minding your pluses and dashes again. Apple so far supports only double-layer DVD+R media, not the DVD-R equivalent that’s just now reaching the marketplace. (Careful readers will note that even as the DVD-format wars seems to be spluttering, they have expanded into the linguistic realm: Apple is following the DVD+RW Alliance in calling two-layer +R discs “double-layer,” even though the -R association Apple has previously been aligned with, the DVD Forum, insistently refers to its version as “dual-layer.”)