Date calculation and display

The graphical view shows work dates based on a work record's scheduled start and scheduled finished dates, if they are available. If no dates are defined for the work, the segments are shown based on other criteria.

Start and end dates and project offset dates

The Start Date and End Date fields control the work period calendar that shows in the graphical view. If a value is defined in the Rolling Offset in Days field in the Roll Schedule window, it is added to either side of the date range in the graphical view. You cannot move work segments outside the graphical view date range as calculated by these fields.

Initial scheduling

The following rules are used to calculate dates for work records in schedules:
  1. If both schedule dates exist (scheduled start and scheduled finish), they are used.
  2. If one schedule date exists (scheduled start or scheduled finish), the other date is calculated by adding (to schedstart) or subtracting (from schedfinish) the duration.
  3. If target dates exist (targstartdate and/or targcompdate), they are used.
  4. If no dates exist, the records are scheduled by their duration, beginning at the current system date.

Parent-child relationships

If a child work order or task has no dates that can be used, it uses its parent's dates if they exist. If a child work order or a task has dates that can be used, they override the parent's dates. The parent's dates are a summary of the start of the earliest child or task through the end of the latest finish date of any of the children.

Completed, closed, and canceled work

Completed records are shown in the schedule as gray read-only bars, using their actual start and actual finish dates.

Closed and canceled work orders are not included in the schedule, even if the work order query on the schedule's main tab includes them.

Precedence constraints

Precedence constraints determine the order of scheduling by establishing dependencies between work orders or tasks. Precedence constraints can be inserted, edited, and deleted directly in the graphical view.

Precedence constraints can be finish-to-start, finish-to-finish, start-to-start, or start-to-finish. They can have lead time (overlaps or head starts) or lag time (gaps or delays).

The constraints can come from a job plan or from work orders that were linked to their predecessors beforehand. Inserting or changing a link does not immediately change the schedule dates. They are processed as part of critical path method (CPM) scheduling when it is run.

Only links between work orders at the same level under the same parent or between tasks of the same work order, are allowed. To graphically manage links between your work orders, you can organize them into a work package under a parent work order in Work Order Tracking. Your work query can fetch that one work order, and all children and tasks automatically become part of the schedule.

To graphically manage links between your work orders, you can organize them into a work package under a parent work order in Work Order Tracking. Your work query can fetch that one work order, and all children and tasks automatically become part of the schedule.

Critical path method (CPM)

In graphical scheduling applications, CPM is a process that determines the schedule dates for the work records. CPM uses durations, precedence constraints, and working time to schedule work. It does not consider resource availability.
  1. The schedule begins at the overall schedule start date (or today). Records without predecessors are scheduled. If the Preserve Schedule Start Dates check box is selected, the dates are unchanged from the last saved session. If the Preserve Schedule Start Dates check box is cleared, the start dates move to the schedule start (or today).
  2. If a record has a start date, CPM considers its interruptible state. If a record is interruptible, its duration is scheduled to occur only during working time according to the schedule’s calendar and shift. An interruptible work record can result in the record splitting around a non-work period. It can also result in a record’s start date moving forward to the next working period, if its original date fell in a non-work period. If the work is not interruptible, the record is scheduled as soon as possible, regardless of calendar and shift.
  3. Successor records are evaluated. The precedence type and lead or lag time is applied to the predecessor’s start or finish date to derive the successor’s start or finish date. Duration is added (to the start) or subtracted (from the finish) to calculate the other date. The record’s successors are then scheduled, and so on, until there are no successors. The total span of that work is rolled up to its parent record. Parent schedule dates are always calculated from the children and are not editable in the graphical view.