P values of the nonmodal partial melting model depend on the melting mode. Different Pvalues will result in variation of melt composition. Abundances of compatible and weakly incompatible elements in melt vary greatly when P values chanse, so P values of these elementscan not be replaced by D0 in the melting model. However, abundances of moderately and highly incompatible elements only show small variation when P values are different. It is thoughtthat P values of moderately and highly incompatible elements are equal to D0 values in the nonmodal partial melting model. When P values are different, a primary rock may form melts different in LREE enrichment or depletion under the same degree of partial melting.