Patent ID: 8432779
Filing Date: 2013-04-30
Classification: G11B

Abstract:
1. A computer readable medium including an information area including a lead-in area, a data area and a lead-out area, each area including a plurality of sectors with sector identifiers, comprising: disc identification information identifying the type of the computer readable medium and recorded in an area preceding the lead-in area, wherein the type of the computer readable medium is one of Read-Only, Recordable, and Rewritable types, the disc identification information recorded as a physical mark and used to control data recording or reproduction to or from the data area, wherein data is recorded in the data area in a format unique to the type of the computer readable medium so that reproduction of the data recorded in the data area of the computer readable medium is selectively restricted based on comparison between the disc identification information and the format of the data, wherein the reproduction of the data recorded in the data area is performed when the disc identification information indicates the Read-Only type and the format of the data is the Read-Only format, and the reproduction of the data recorded in the data area is not performed when the disc identification information does not indicate the Read-Only type and the format of the data is the Read-Only format, and wherein the physical mark is recorded to have a pattern of repeated mark/space pairs with respect to a monotone high-frequency modulated groove, each mark/space pair consists of a mark and a space each having a length, and the length of the marks and spaces in each section of 36T is determined in accordance with a data value associated with the section such that all marks and spaces in the section of a value of “1” have a length of 3T, and all marks and spaces in the section of a value of “0” have a length of 9T.