A Semi-supervised Approach to the Selection of Specifications Forms in a Universal Services Marketplace.

In an optical disk having a recording plane having a spiral first track and a spiral second track, information being to be recorded into and/or reproduced from said first and second tracks, the first track is formed into a groove-like shape, the second track is formed between adjacent the first tracks and into a land-like shape, and the first and second tracks record informations in different modulation methods.