That's a tree based molecule language with the parens right? This must be for organic molecules mostly then because you can repeat atoms as in, i.e. crystal molecules?
SMILES is usable for any molecule (i.e. any compound with covalent bonds; crystals are generally not considered molecules), though it's most common use is for organic molecules. Parens indicate branching, and cycles are conceptually treated as branches that revisit the same atom twice.
