A Plant Service Order (PSO) is an instance of service for a Plant Item, the nature of which is defined in the Plant Policy from which the PSO is created.
PSO's can be created without the use of a Policy, but are then treated as one off service jobs.
Typically planned maintenance will involve a sequence of PSO's recurring at certain intervals. The first PSO in the sequence will be set up manually, using a Plant Policy as the basis of the defaults. Subsequent PSO's in the sequence will be automatically created when the previous PSO is completed, based on the Service Interval and the Recurring setting.
Alternatively a PSO may be a one off instance of service for a Plant Item. Whilst these one off's could be manually entered, it is suggested that a Plant Policy be set up to provide some of the defaults to make the creation easier. Such PSO's would have the Recurring value set to None.