Ozone depletion as the International Day for the Preservation of the Ozone Layer, or "World Ozone Day", to commemorate the signing of the Montreal Protocol on that date in 1987. Ozone depletion Ozone depletion describes two related events observed since the late 1970s: a steady lowering of about four percent in the total amount of ozone in Earth's atmosphere (the ozone layer), and a much larger springtime decrease in stratospheric ozone around Earth's polar regions. The latter phenomenon is referred to as the ozone hole. There are also springtime polar tropospheric ozone depletion events in addition to these stratospheric events. The main
Layer Jump Recording versa. Jumping layers is already necessary for reading multiple layer optical media (so far market released products are limited to two layers despite some research prototypes having up to eight layers), as well as for recording them with Sequential Recording. However the layer jump during the recording occurs only once, at the position called Middle Area, during a Sequential Recording, while it may occur multiple times with Layer Jump Recording. Two different Layer Jump methods are defined: Manual Layer Jump and Regular Layer Jump. The first require the software to specify to the hardware each jump point from layer zero