High pressure fuel pump duty limit
For direct injection vehicles this will limit the air charge / cylinder filling / boost based on the fuel pump duty in order to prevent the fuel pump from running out of volume.
Fuel pump target is the duty percentage the air charge will be limited. Fuel pump hysteresis is the duty percentage where the protection is removed. The hysteresis should be the same value or lower than the target value.
The fuel pump volume delivered per cycle is not proportional to duty percentage since the fuel pump piston is driven from a lobe which is not triangular, but is close to a sine curve. eg going from 90% duty to 100% duty does not give 11% more fuel but more like 2.5% more fuel.