This Microsoft Excel workbook (2.712 Mb) contains spreadsheets that implement the Updated Bottom Up Solution for Triacylglycerols that allows Critical Ratios that provide structural information from mass spectrometry to be used to reconstitute the original mass spectra from which they came. It contains spreadsheets that use the non-nested equations (Critical Limits explicitly shown), as well as spreadsheets that used the nested equations (Case determinations made with Critical Limits not explicitly shown).