Index marks on CD’s: “What are the purpose of index marks on CD’s? I see these on commercial CD’s all the time even though they don’t seem to point to anything particular in the music.”
Index marks can be used for a variety of reasons, but in general they should and do have something to do with the music. For example, in a long piece of music indexes are often used to denote specific sections. Some CD players have the ability to search and play specific index points in the same way most CD players can play specific track numbers. Due to the fact that many of today’s CD players do not recognize index points their use has declined in recent years and ultimately may disappear altogether.