The ProteomeXchange (PX) Consortium has been receiving and making public proteomics datasets from the community since 2012, and PX members are highly active in the PSI. The datasets themselves always remain at the receiving repository for a submission, but the most important metadata about each experiment is transmitted from the receiving repository to ProteomeCentral whenever a dataset is made public. The common format for this is PX XML (current version is 1.4, ), which encodes study metadata such as title, description, submitter, publication, location of availability, submitted files, etc. The format is similar to mzML and mzIdentML in basic design and since its development in 2011 has evolved to include an increasing amount of metadata as ProteomeXchange requirements increase.