The DURATION statement identifies the variable in the Activity data set that contains the length of time necessary to complete the activity. If the network is input in AOA format, then the variable identifies the duration of the activity denoted by the arc joining the TAILNODE and the HEADNODE. If the network is input in AON format, then the variable identifies the duration of the activity specified in the ACTIVITY statement. The variable specified must be numeric. The DURATION statement must be specified. The values of the DURATION variable are assumed to be in interval units, where interval is the value of the INTERVAL= option.

If you want the procedure to compute the durations of the activities based on specified start and finish times, you can specify the start and finish times in the Activity data set, identified by the variables specified in the START= and FINISH= options. By default, the computed duration is used only if the value of the DURATION variable is missing for that activity. The duration is computed in units of the INTERVAL= parameter, taking into account the calendar defined for the activity.

In addition to specifying a fixed duration for an activity, you can specify the amount of work required (in units of the INTERVAL parameter) from each resource for a given activity. The WORK variable enables you to specify resource-driven durations for an activity; these (possibly different) durations are used to calculate the length of time required for the activity to be completed.