For spectral library searching, SpectraST has been a TPP tool since its original development. With this approach, new spectra are matched against a library of previously identified spectra in the form of a spectral library. This approach is much faster, more sensitive, and more specific than sequence database searching, although is only as good as the reference spectral library provided. There is renewed interest in spectral libraries because of data-independent acquisition (DIA) approaches being increasingly deployed and therefore the quality and coverage of libraries is very important and likely to improve in the coming years, aided by a new standard spectral library format being developed by the PSI (). Furthermore, the approach is complementary to sequence searching since new data can be searched with both SpectraST and a sequence search engine and then merged into a combined, better result with iProphet (described below). SpectraST is capable not just of searching new data, but also of creating high-quality libraries based on the output of TPP searches as well as generating decoy libraries .