A modified AV/C command set includes status inquiry, notify inquiry and control inquiry commands. The status inquiry, notify inquiry and control inquiry commands include an opcode and any number of operands. Thus, the status inquiry, notify inquiry and control inquiry commands can include only an opcode....http://www.google.com/patents/US20030070028?utm_source=gb-gplus-sharePatent US20030070028 - Method and apparatus for utilizing extended AV/C command frames including status inquiry, notify inquiry and control inquiry command types
