This specification defines the detailed specifications for Rec. ITU-R BO. 1294 System B data structures which are used by an AV/C tuner subunit that supports Rec. ITU-R BO. 1294 System B. The AV/C tuner defines a model and command set for analog and digital tuners operating over IEEE 1394-1995. The command set makes use of the Function Control Protocol (FCP) defined by IEC 61883, Digital Interface for Consumer Electric Audio/Video Equipment standard, for the transport of audio/video command requests and responses. The audio/video devices are implemented as a common unit architecture within 1394-1995.