Seeking help with questions regarding the suction lift of pumps and the required net positive suction head!

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Regarding centrifugal pumps, there has always been a problem, and I would like to ask the experts here! After the process layout of the centrifugal pump is completed and the effective net positive suction head available, NPSHA, is calculated, it needs to be compared with the required net positive suction head required by the pump, NRSHR. But pump manufacturers usually specify a suction lift. What exactly is this concept of suction lift? Check the references. Suction lift = Atmospheric pressure (10.33 m) – NPSH – Safety margin (0.5 m) ； What is the net positive suction head in this formula? What is net positive suction head? Is it NPSH, NPSHA, or NPSHR? Personally, I think since NPSHR is a parameter related to the pump, and head lift is also a parameter of the pump, isn’t the net positive suction head available in the head lift formula equivalent to NPSHR?