Loadable/saveable chemistry file formats

.cml CML files are a chemistry implementation of the the XML standard for coding information. See the CML homepage for more.
.mol MDL mol files. A de-facto standard file format [ DAL92 ] invented by the company Molecular Design Ltd. The MDL people call this an SD file.
.sdf May contain multiple molecule in SD format, separated by a "$$$$" line. JChemPaint opens one frame for each structure it finds.