Abstract: A magnetic disc used in a constant-density magnetic disc driving apparatus includes a wedge identification field following a servo information area that contains a wedge identification for identifying a plurality of data sectors located within a corresponding data information area. A pseudo identification field positioned at a first portion of each data sector represents a time interval required to generate from the wedge identification a pseudo identification that identifies a corresponding one of the data sectors and transfer the pseudo identification to a controller of the magnetic disc driving apparatus. The pseudo identification field includes a data preamble for providing data synchronization for the corresponding data sector. A data field is positioned behind the pseudo identification field, and the data field and pseudo identification field make up a single data sector. Data that is identified by the pseudo identification and synchronized by the data preamble is written in the data field.