An optical system for an optical head of an optical disc drive is capable of using first and second discs, protective layer of the second disc being thicker than that of the first disc, a data density of the second disc being lower than that of the first disc. The composition so described is used to prevent the degradation of extracellular matrix, stabilize connective tissue, is used to as an antioxident, and is used for treating damage to skin comprising applying the topical composition to the skin. The port is formed of an inner side located between a center of the exit wall and an outer edge of said the wall, an outer side located between the inner side and the outer edge of the exit wall, and two opposing secant sides connecting respective ends of the outer side to the inner side. The original format of the materials may be limited to a master data format, eg. A message unit then is produced in the memory for each of the set of message segments that does not have an existing message unit in memory.