Field help (WST5) 

Filter for results within a range of planned work centers. For a single work center, enter the same work center code in the from/start Work center and to/end Work center fields.

The planned work center is attached to a work center group. It corresponds to a production resource on which a routing operation is to be carried out.
It is an entity for which the load needs to be planned and/or the production times need to be tracked.