Mathematical treatment is attempted in this paper to illustrate the orientation relation-ship between PT and Pμ bundles, emphasizing that conflicting orientation cannot be precludedbetween the two different kinds of bundles on thermodynmic basis. An explanation is alsogiven to the fact that why orientations are found consistent between most PT and Pμ_wbundles but contradictions are frequently observed between them when chemical potential ofa volatile rather than water is used as an intensive variable. Mathematical treatment is attempted in this paper to illustrate the orientation relation-ship between PT and Pμ bundles, emphasizing that conflicting orientation can not be precluded between the two different kinds of bundles on thermodynmic basis. An explanation is alsogiven to the fact that why orientations are found consistent between most PT and Pμ_wbundles but contradictions are frequently observed between them when chemical potential of a volatile rather than water is used as an intensive variable.