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. The ZONE= option enables you to divide the network diagram into horizontal bands or zones corresponding to this classification. The procedure uses the following rules to place the nodes in a zoned network diagram:

• The values of the ZONE variable are used to define as many zones as there are distinct values of this variable.

• Each node of the network is drawn within its corresponding zone.

• The number of rows within each zone is determined by the maximum number of nodes in any given column that correspond to that zone.

• The values of the ZONE variable do not need to be sorted in any particular order, nor do they need to be grouped by distinct values.

• The zones are ordered according to the order of appearance of the different values of the ZONE variable in the Network data set. This enables you to choose any order for the zone values.

• For arcs that connect two nodes within the same zone, the arc lies entirely within the zone; in other words, all the turning points of the arc have coordinates that are between the minimum and maximum coordinates for the zone.

• Each zone is labeled by the value of the ZONE variable unless the
  NOZONELABEL option is specified.

• Each zone is separated from the next by a horizontal line drawn across the width of the network unless the NOZONELABEL option is specified.

• In the graphics and full-screen modes of invocation of the procedure, you can use the ZONEPAT option to color the nodes in each zone differently using different pattern statements. In the graphics mode, the first zone uses the first PATTERN statement, the second zone uses the second PATTERN statement, and so on; in full-screen mode, the colors available for the device are repeated in cyclic order. Note that the values of the PATTERN variable (or the default _PATTERN variable, if it exists in the Network data set) override the node patterns dictated by the ZONEPAT option.