On a CD, MD, or OD, microscopic depressions laser-burned into the surface on which the digital data is stored. Each pit-edge encodes a 1 in the datastream. Incremental lengths of flat disc surface (either land between pits or the bottom of an extended pit) designate zero0s in the data. Audio samples, location and synchronizing information, bands and indexing, visual information, etc. are all encoded in the pits.