The PSI-PAR format is a standardized means of representing protein affinity reagent data. The PSI-PAR format consists of the PSI-MI XML2.5 schema (originally designed for molecular interactions) and the PSI-PAR controlled vocabulary. Strictly speaking it is not a separate file format; the Proteomics Standards Initiative page describing PSI-PAR says there are no changes to the structure of the PSI-MI XML2.5 schema, although some schema element descriptions have been modified.
Gloriam, D. E., Orchard, S., Bertinetti, D., Björling, E., Bongcam-Rudloff, E., Borrebaeck, C. a K., Bourbeillon, J., et al. (2010, January). A community standard format for the representation of protein affinity reagents. Molecular & cellular proteomics : MCP. doi:10.1074/mcp.M900185-MCP200