A process unit status transition says that a process unit may change from one status to another. A process unit can, for example, go from the status "Ordered" only to "Invoicable". The subject "Process Unit Status Transitions" registers the allowed transitions. The screen has these fields: - "Number": the unique sequence number of the transition. - "Process Unit Status Old": the status the process unit has before the change. The field can be empty for the first status of a process unit. - "Process Unit Status New": the status the process unit has after the change. - "Explanation": an optional note of the administrator on the meaning of the transition. See [[Invantive Estate/Subjects/Advanced/Process Unit Status|Process Unit Status]].