Field help (EFF) 

Efficiency is a way to measure compliance to the preset standards. It can be calculated over a given period by work center: Standard hours calculated for a given production divided by the actual hours worked.
Efficiency makes it possible to correct the standard times of the routing (multiplying factor) according to the used resource.

Two efficiency rates are managed depending on the following:

If both factors are entered, they add up.
The calculated operating time is corrected in the following way: work center efficiency * operation efficiency * time.

The WSTEFFINH - Work center efficiency history parameter (GPA chapter, MIS group) is used to specify whether the efficiency defined at work center level should be used on the routing operation.