 or 20 or SO low quality mono services. It is possible to alter the data rate according to the requirements of the programme SO that maximum use is made of the available capacity. Additional data services are also available. The transmitted data is used for a variety of different services. The primary one is obviously the audio. This can be apportioned as required and can be selected to be between 32 and 384 kbits per second, allowing Broadcasting 219 typically up to six high quality stereo transmissions or up to 20 restricted quality mono programmes, or a mixture as required. Programme associated data (PAD) is embedded in the audio bit stream and is used for data transmitted in support of the audio programme. It may include information about the track in the form of the artist's name, the title of the track, lyrics, or even graphics for display on the receiver. The data may also be used for facilities such as dynamic range control. Like the audio data rate, the programme associated data rate is adjustable, but with a minimum data rate of 667 bits per second and a maximum of 65 kbits per second. In addition to the PAD, general data may be transmitted as a separate service. This can be achieved in a number of ways. It may be via what is termed the fast information channel (FIC) or it may be as packets of data in a packet sub-multiplex. This service may be used for a variety of purposes from a traffic message channel to an electronics newspaper. Data may also be transmitted to support pay to listen services. Conditional access (CA) data may be transmitted, although the format for this is not defined yet. This is expected to be determined by the subscription service using the facility. Further data in the form of service information (SI) is transmitted. This is used for the control of receivers and to provide information for programme selection to the user. It can also be used to provide links between different services in the multiplex. It can even be used to provide links to services in other DAB multiplexes or en