Hi,
Hard to guess, for me. Perhaps it just means that the voltage referred to ground before the shunt, from ground to the resistor positive terminal, is the full supply voltage, the "Vcm - Vshunt" means the voltage referred to ground minus the shunt resistor's voltage drop when measured at the resistor negative terminal.
Presumably the difference inferred is the voltage across the resistor to measure the current Iload. So maybe it's trying to explain current shunt measurement, e.g. measuring the voltage across the resistor based on V1 - V2/R = I(load).