Populated by ((Chem molar mass/format)) (talk). That template can take a value in any of several different parameters; this category tracks when more than one is passed. It is called via ((Chem molar mass)) (talk) from ((Infobox drug)) (talk). In that context, it tracks pages that have a molecular formula specified by individual element parameters (|C=...|H=......), which triggers the template to auto-calculate the molecular weight, when there is also an explicit |molecular_weight= value.