Individual resources can join ProteomeXchange by implementing the ProteomeXchange data submission and dissemination guidelines, and metadata requirements. In the current version (http://www. proteomexchange. org/concept), the mandatory information includes the following: first, mass spectrometer output files (raw data, either in a binary format, or in a standard open format such as mzML); second, processed identification results (two submission modes are available, see below); and third, sufficient metadata to provide a suitable biological and technological background, including method information such as transition lists in the case of SRM data. Other types of information, such as peak list files (processed versions of mass spectra most often used in the identification process) and quantification results can also be provided.