The correspoonding curve are :
Lower left to 1 - thesublimation curve of rhombic s : s(rhombic) s(g).
1 to 2 - the sumlimation curve of monoclinic : s (monoclinid) s(g).
2 to upper right - the vapor pressure curve of liquid s : s(l) @(g).
1 to 3 - the transition curve for s(rhombic) s(monoclinic).
2 to 3 the melting point curve for s(monoclinic) s(l).
3 to top - the melting point curve for s(rhombic) s(l).