The Unique ID field contains the number that Microsoft Office Project automatically designates whenever a new task, resource, or assignment is created in the current project. This number indicates the sequence in which the task, resource, or assignment was created, regardless of placement in the schedule.
There are several categories of Unique ID fields.
Data Type Integer
Unique ID (task field)
Entry Type Calculated
How Calculated As you create new tasks, Project adds a unique number to each task in the project. This number is unique in that it is never rearranged or reused if the task is moved or deleted.
Best Uses Add the Unique ID field to a task sheet when you want to display or filter the unique ID for tasks.
Example You want to review tasks by the order in which they were created. In the Task Sheet view, you sort the tasks by the Unique ID field.
Remarks If tasks are moved, inserted, or deleted, the task IDs change to reflect the new task sequence. However, the Unique ID always remains constant, regardless of any editing.
Unique ID (resource field)
Entry Type Calculated
How Calculated As you add resources, Project assigns a unique number to each resource within the project. This number is unique in that it is never rearranged or reused if the resource is moved or deleted.
Best Uses Add the Unique ID field to a resource sheet when you want to display or filter the unique ID for the resource.
Example You want to review the project's resources by the order in which they were added to the project. In the Resource Sheet view, you sort the resources by the Unique ID field.
Remarks If resources are moved, inserted, or deleted, the resource IDs change to reflect the new sequence. However, the Unique ID always remains constant, regardless of any editing.
Unique ID (assignment field)
Entry Type Calculated
How Calculated As you assign tasks to resources, Project adds a unique number to each assignment within the project. This number is unique in that it is never rearranged or reused if the assignment is moved or deleted.
Best Uses Add the Unique ID field to the sheet portion of the Task Usage or Resource Usage view when you want to display or filter by the unique ID for the assignment.
Example You want to review the assignments in the order that they were made. In the Task Usage view, you sort the assignments by the Unique ID field. Project sorts first on the tasks' Unique ID field, and then on the assignments' Unique ID field within the tasks.
Remarks If an assignment is inserted or deleted, the IDs change to reflect the new sequence. However, the Unique ID always remains constant, regardless of any editing.