Write-once type information storage medium (disk structure of recording type information storage medium having structure in which recording layer formed on transparent susbstrate is defined as inside), and information reproducing method or information recording method as well as storage medium manufacturing

An information storage medium comprising:

• a substrate formed in a disk shape;
• and
• a recording layer which is formed on or above the substrate, the recording layer comprising a spiral track having a pre-groove configured to reproduce a push-pull signal, a track pitch of the spiral track being 500 nm or less, the pre-groove being wobbling to provide wobble detection signals, and at least a part of the pre-groove being modulated with Frequency Shift Keying,
• wherein the pre-groove is configured to generate a difference signal and an adding signal,
• wherein the push-pull signal is indicative of a first ratio of the difference signal to the adding signal, the first ratio being not less than 0.1 and not more than 0.8,
• wherein the information storage medium comprises a Low to High characteristic and is configured to record a mark regarding a minimum inversion length of 2T,
• wherein a second ratio of a first signal amount to a second signal amount is more than 0.2, where the first signal amount represents a reproduction signal amplitude relating to an inversion length of 3T, and the second signal amount represents another reproduction signal amplitude relating to a mark regarding a maximum inversion length, and
• wherein a value-of Wppmax/Wppmin is 3 or less, where Wppmax and Wppmin are the maximum and minimum amplitude values of the wobble detection signals, respectively.