It appears the major sticking point concerns the depth of the memory layer on which data is written: HD-DVD favors a data layer 0.6mm beneath the surface of the disk, the same depth as on the current generation of DVDs.

ENGADGET: DVD format war: Matsushita says Toshiba needs to give up

The depth of the water layer is crucial.

ECONOMIST: Using ski wax can trap dirt, and thus slow down the skier

Dual-shot adds a second layer of colored, transparent or translucent polycarbonate on top of a base layer to produce secondary color blends and depth effects.

ENGADGET: Nokia Lumia 620 announced: 3.8-inch WVGA display, 5MP camera, $249

Rather than complex texture maps, Tearaway uses layer upon layer of plain colored paper to give a real sense of depth.

FORBES: Vita Exclusive Tearaway Includes Paper-Craft Achievements

This is made possible by the fact that Blu-ray uses a 405nm laser to read its 0.1mm deep info layer, while HD DVD uses the same blue laser wavelength at the depth of 0.6mm.

ENGADGET: Three's company: Warner patents all-in-one hybrid disc HD