FAIRsharing record for: HUPO-PSI Universal Spectrum Identifier

This FAIRsharing record describes: The Universal Spectrum Identifier (USI) is multi-part key identifier for identifying mass spectra contained in public data repositories, primarily focused on proteomics. The USI provides a standardized mechanism for encoding a virtual path to any single mass spectrum generated by a mass spectrometer contained/deposited to public proteomics dataset repositories for enabling greater transparency of spectral evidence. With more than 1 billion USI identifications from over 3 billion spectra already available through ProteomeXchange repositories, Universal Spectrum Identifier encodes the dataset, the MS Run, the scan number and the proposed peptidoform and charge of the ions responsible for the spectrum. The USI identifier is comprised of five key components (and an optional sixth component) in defining an abstract path to a specified spectrum. The USI core components include: 1) the prefix ‘mzspec’ to make clear that the following string is a USI and to aid in automated mapping of a USI string to a URL, 2) the subsequent dataset submission or dataset collection identifier assigned by the primary repository archive, 3) the mass spectrometry run name (or root name of the raw vendor format file) such as an mzML file (with or without the file extension), 4) a type flag (such as ‘scan’, ‘index’ or ‘nativeId’ as defined in the current mzML specification) for indicating how to interpret the fifth component, 5) the index value (based on the flag type) within the specified MS run, and optionally 6) any relevant information for interpretation of the spectrum if available.