The Physics and Astronomy Classification Scheme (PACS) is a scheme developed in 1970[1] by the American Institute of Physics (AIP) for classifying scientific literature using a hierarchical set of codes.
[2] PACS has been used by over 160 international journals,[1] including the Physical Review series since 1975.
AIP has announced that PACS 2010 will be the final version, but it will continue to be available through their website.
[1] The decision was made to discontinue PACS, owing to the administrative complexity of the revision process and its future viability in light of changing technological and research trends.
[3] In association with Access Innovations, Inc., the AIP has developed a new "AIP Thesaurus",[4] which it states will enable faster, more accurate and more efficient searches.