Name Description
    A Any (any atom except hydrogen)
    AH Any atom, including hydrogen
    Q Hetero (any atom except hydrogen and carbon)
    QH Hetero atom or hydrogen (any atom except carbon)
    M Metal (contains alkali metals, alkaline earth metals, transition metals, actinides, lanthanides, poor(basic) metals, Ge, Sb and Po)
    MH Metal or hydrogen
    X Halogen (F,Cl,Br or I)
    XH Halogen or hydrogen