The Zone variable is used to divide the network diagram into horizontal bands or zones corresponding to the distinct values of the variable. Most projects have at least one natural classification of the different activities in the project: department, type of work involved, location of the activity, and so on. By specifying a Zone variable, you can use this classification to subdivide the network diagram. The zones are automatically labeled with the Zone variable values and are separated by dividing lines. Click the button to select a Zone variable.