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: variable quantity, which is not influenced by the control but is introduced into the control system from outside with the aim of making the final controlled variable follow it in a given relationship; Name: command variable