The zones are as follows :
Zone O:-Inside the bath tub or shower tray.Any fitting going in this area must be low voltage(12v max)and have an IP rating of at least IP67.
Zone 1:-Directly above the bath tub or shower tray to a height of 2.25m from the floor. Products should be IP44 or higher and if the fitting is 240v a 30ma RCD must be used to protect the circuit.
Zone 2:-Over the bath tub or shower tray above zone 1.It also covers the area stretching 0.6m outside the perimeter of the bath and to a height of 2.25m from the floor and the area around the wash basin,within a 60cm radius of any tap.Lighting in this area should be at least IP44.
This information should be used for guidance only; always refer to the current IEE Wiring Regulations,or a qualified electrician,to ensure that you are guided by the latest codes of practice.