An optional (tentative) identification of the detected features with available fragmentation data is based on SiriusAdapter, an OpenMS tool that invokes an externally provided SIRIUS executable (Figure ). SIRIUS generates formula predictions based on scores calculated from MS 2 fragmentation (ppm error and intensity) and MS 1 isotopic pattern scores. CSI:FingerID is a web service, which, after the formula predictions are uploaded via the SIRIUS executable, uses those formulas to predict their molecular structure fingerprint using a machine learning approach.