The Sybyl Line Notation is an extension of Daylight SMILES. It can
serve as both a file format and for queries:
http://perlmol.org/pod/Chemistry/File/SLN.html
http://dx.doi.org/10.1021/ci960109j
-Geoff
(This entry is for the file format itself. It's related to the Feature request
for query methods.)