Peak Annotation Format (mzPAF)

The mzPAF proposed standard is a specification for a fragment ion peak annotation format for mass spectra, focused on peptides. This provides for a standardized format for describing the origin of fragment ions to be used in spectral libraries, other formats that aim to describe fragment ions, and software tools that annotate fragment ions.


Updated: 2023-02-25

The specification has been submitted to the PSI Document Process and is undergoing review. It will take several months starting January 2023 to undergo rigorous review before potentially becoming a PSI standard.

Your comments and suggestions are still very much welcome. Please submit an issue at the repo to provide your feedback and send an e-mail to the HUPO-PSI editor Sylvie Ricard-Blum (

Available Materials