Page "Simplified molecular-input line-entry system" Paragraph 6

SMILES notation allows the specification of configuration at tetrahedral centers, and double bond geometry.

These are structural features that cannot be specified by connectivity alone and SMILES which encode this information are termed Isomeric SMILES.

A notable feature of these rules is that they allow rigorous partial specification of chirality.

The term Isomeric SMILES is also applied to SMILES in which isotopes are specified.