The ALIGNDATE statement identifies the variable in the Activity data set that specifies the dates to be used to constrain each activity to start or finish on a particular date. The ALIGNDATE statement is used in conjunction with the ALIGNTYPE statement, which specifies the type of alignment. A missing value for the variables specified in the ALIGNDATE statement indicates that the particular activity has no restriction imposed on it.

PROC CPM requires that if the ALIGNDATE statement is used, then all start activities (activities with no predecessors) have nonmissing values for the ALIGNDATE variable. If any start activity has a missing ALIGNDATE value, it is assumed to start on the date specified in the PROC CPM statement (if such a date is given) or, if no date is given, on the earliest specified start date of all start activities. If none of the start activities has a start date specified and a project start date is not specified in the PROC CPM statement, the procedure stops execution and returns an error message. See the section Time-Constrained Scheduling for information about how the variables specified in the ALIGNDATE and ALIGNTYPE statements affect the schedule of the project.