Assigning Profitability Segments 
Use
In contrast to other assignment objects,
Profitability Segments do not have master records. A profitability segment is a combination of characteristics, such as a customer, product, plant, distribution channel, and so on. One of these characteristics is always the profit center. Like all the other characteristics, the system supplies the profit center with a value when data is posted to a profitability segment. The profit center can be derived automatically from the material/plant or other characteristics. Alternatively, you can enter it manually. For more information on profitability segments, see the section
CO Profitability Analysis in the R/3 Library.The data which is posted to a profitability segment is also updated in the profit center which is specified in the profitability segment's characteristic.