Mixed-mode refers to a CD-Digital Audio disc with computer data included. Often, the data (programs, movies, indexes, etc.) are contained in track #1, which conforms to the Mode 1 (ISO 9660) standard. Audio begins in track #2, and can be up to 98 standard CD tracks. Early CD players did recognize the first data track, and would ‘play’ it, which resulted in loud noise at the output of the player. Modern CD players do not have this problem. There have been several implementations of the mixed-mode disc using different structures. Some put the data at the end, while others have a separate session of a multisession CD for the data.