However, the term SMILES is also commonly used to refer to both a single SMILES string and a number of SMILES strings the exact meaning is usually apparent from the context. The term SMILES refers to a line notation for encoding molecular structures and specific instances should strictly be called SMILES strings.
SMILES is generally considered to have the advantage of being more human-readable than InChI it also has a wide base of software support with extensive theoretical backing (such as graph theory). In July 2006, the IUPAC introduced the InChI as a standard for formula representation. Other 'linear' notations include the Wiswesser Line Notation (WLN), ROSDAL and SLN (Tripos Inc). In 2007, an open standard called "OpenSMILES" was developed by the Blue Obelisk open-source chemistry community. It has since been modified and extended by others, most notably by Daylight Chemical Information Systems. Acknowledged for their parts in the early development were "Gilman Veith and Rose Russo (USEPA) and Albert Leo and Corwin Hansch (Pomona College) for supporting the work, and Arthur Weininger (Pomona Daylight CIS) and Jeremy Scofield (Cedar River Software, Renton, WA) for assistance in programming the system." The Environmental Protection Agency funded the initial project to develop SMILES. The original SMILES specification was initiated by David Weininger at the USEPA Mid-Continent Ecology Division Laboratory in Duluth in the 1980s. 4 SMILES definition as strings of a context-free language.