The ability to focus SoM annotation efforts on the most informative atoms among collections of molecules is of particularly high relevance because of the specifics of measured metabolism data. This data originates primarily from liquid chromatography-mass spectrometry (LC-MS) experiments and is often concerned with substantial uncertainty about the exact location at which a biotransformation occurs (Figure ). Therefore, an objective method capable of cherry-picking, across collections of molecules, the most relevant atom positions for annotation, can be of enormous help to expert curators in focusing their experimental efforts. The application of such a method could result in more accurate and informative data.