PROC CPM does the project scheduling and forms the core of the project management functionality in SAS/OR software. It uses activity precedence, time, and resource constraints, and holiday and calendar information to determine a feasible schedule for the project. The precedence constraints between the activities are described using a network representation, either in Activity-On-Arc (AOA) or Activity-On-Node (AON) notation, and input to PROC CPM in an Activity data set. The two different representations are described in Chapter 4: The CPM Procedure. The Activity data set can also specify time constraints on the activities and resource requirement information. The Activity data set is required. Resource availability information can be specified using another data set, referred to here as the Resource data set. Holiday, workday, and other calendar information is contained in the Holiday, Workday, and Calendar data sets; each of these data sets is described in detail in Chapter 4: The CPM Procedure. The schedule calculated by PROC CPM using all the input information and any special scheduling options is saved in an output data set, referred to as the Schedule data set. For projects that use resources, individual resource schedules for each activity can be saved in a Resource Schedule output data set. Resource usage information can also be saved in another output data set, referred to as the Usage data set. Figure 3.1 illustrates all the input and output data sets that are possible with PROC CPM. In the same figure, _ORCPM_ is the SAS macro variable defined by PROC CPM.

The three output data sets produced by PROC CPM contain all the information about the schedule and the resource usage; these data sets can be used as input to either PROC GANTT or PROC NETDRAW or to any of the several reporting, charting, or plotting procedures in the SAS System.

The Schedule data set can also contain additional project information such as project ID, department and phase information, accounting categories, and so on, in the form of ID variables passed to it from the Activity input data set with the ID statement. These variables can be used to produce customized reports by reordering, subsetting, summarizing, or condensing the information in the Schedule data set in various ways.