Generic Query Atoms

Name	Description
A	Any (any atom except hydrogen).
AH	Any atom, including hydrogen.
Q	Hetero (any atom except hydrogen and carbon).
QH	Heteroatom 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.