HUPO PSI-PAR: standard format for protein affinity reagents is now available for Public Comment on the PSI Web site for the next 30 days. The public comment period enables the wider community to provide feedback on a proposed standard before it is formally accepted, and thus is an important step in the standardisation process. This message is to encourage you to contribute to the standards development activity by commenting on the material that is available online. We invite both positive and negative comments. If negative comments are being made, these could be on the relevance, clarity, correctness, appropriateness, etc, of the proposal as a whole or of specific parts of the proposal. If you do not feel well placed to comment on this document, but know someone who may be, please consider forwarding this request. There is no requirement that people commenting should have had any prior contact with the PSI. If you have comments that you would like to make but would prefer not to make public, please email the PSI-Editor directly.