An interface and protocol allow a media player to communicate with external accessories over a transport link. The protocol includes a core protocol functionality and a number of accessory lingoes. Examples of accessory lingoes include a microphone lingo, a simple remote lingo, a display remote lingo,...http://www.google.com/patents/US8171195?utm_source=gb-gplus-sharePatent US8171195 - Media player communication with an accessory using a display remote lingo
