Description: Head observed at inlet area of the installation, corresponding to the sum of the height, pressure head and velocity head  ; Name: Total head at inlet area of the installation
Description: Determined total head at the inlet area of the installation, which corresponds to the sum of geodetic head, pressure head and velocity head; Name: Total head at inlet area of the installation
Description: Probability that an item is in a state to perform as required at a given instant, under given conditions, assuming that the necessary external resources are provided ; Name: Instantaneous availability