In MS2-MS2-MS3 experiments, the crosslinked peptide is first fragmented into single peptides by breaking the crosslinker. The peptide fragments are isolated from the MS2 scan and fragmented as single peptides in the MS3 spectra. All four MS3 spectra of the crosslinked peptides contain only a single peptide that is specified in the label on top of the spectrum. This strategy contains an additional MS2 spectrum, which typically uses another fragmentation type, for example, ETD and displayed under the MS2 diagnostic scan as shown in Crosslink Spectrum Match Identification Details View.