Dynamic Visualization of Proprietary Mass Spectrometry Data Files. The Peak Viewer tool in multiplierz provides interactive plots for precursor RICs, and corresponding MS and MS/MS scans, in centroid or profile modes. Green squares in the RIC denote MS scans and red triangles indicate MS/MS events. In addition, users may adjust the time or m/z range displayed in each data window. Verification of peptide sequence is facilitated by overlay of theoretical fragment ions on the MS/MS spectra. Users may dynamically evaluate multiple peptide assignment options by changing the proposed sequence or post-translational modification state in the left-most pane.