FIELD: information technology.
SUBSTANCE: data medium has a plurality of data storage layers, each having an optimum power control region used to obtain an optimum writing state, buffer regions and a display-only region which stores data for displaying only. The display-only region of one of the data storage layers lies opposite the optimum power control region and buffer regions of one of the neighbouring data storage layers.
EFFECT: higher writing quality.
2 cl, 18 dwg
