No, there is no “H” missing here, the p-value also exists and it is even related to the m-value: The p-value is the measure of the strong alkalis dissolved in water. It too owes its name to a color indicator, namely phenolphthalein. It is colourless up to a pH of approx. 8, then it turns into purple and finally becomes colourless again after a value of approx. 12.