Although not formally ratified by the PSI, the PSI supported the development of the HUPO Human Proteome Project (HPP) Mass Spectrometry Data Interpretation Guidelines. Three such versions have been produced. The 1.0 version of these guidelines described the repository deposition requirement for data contributed to the HPP (). Version 2.1 of the guidelines added additional requirements for false-discovery rate (FDR) thresholding and for evidence supporting claims of detection of human proteins. Version 3.0 of the guidelines further refined these ideas to provide more stringent requirements for exclusion of false positives. Version 3.0 was published in 2019 and no further refinements seem necessary as of 2022.