Capacity Categories 
Capacities in work centers are distinguished by capacity categories Capacity categories are for example:
- Machine capacity
- Personnel capacity
- Reserve capacity for rush orders
- Emissions
- Energy requirements
Each capacity category can be used once in each work center. For every capacity category you can maintain several available capacities ( standardavailable capacity and available capapcity versions)
You define capacity categories in Customizing Work Centers under Define Capacity Categories.