ExternalSystemIdentifier

String (50)

One of ExternalSystemIdentifier or ProjectTaskUid is required

The external system identifier is a unique identifier for a project task(may be null, but once set can only be updated to a different, non-null value).

ESI-123

ProjectTaskId

Int32

On Insert: No

On Update: No

The project task Id is a unique identifier for a project task. For internal use only.

ProjectTaskUid

Int64

See ExternalSystemIdentifier

A unique and immutable identifier for a project task.

1152921504608637358