This question is based on the requirements of a system to record band bookings at gigs. (A 'gig' is an event at which one or more bands are booked to play). You do not need to know about the full system and you should base your answer to this question on the following extract of the design.

Part of the design of the static data is represented by the following entity relationship diagram.

The main attributes of these entities are:

When a booking is made for a gig, the band and the gig need to be identified, and input provided for the length of the spot, and whether the band uses its own sound system. Where the band uses its own sound system the Tech_Phone value should be printed to the screen.