PACS: Physics and Astronomy Classification Scheme®

What is PACS?

How to use PACS

PACS Scheme 2003(and previous)

PACS numbers have been used in Physical Review since 1975 to identify fields and sub-fields of physics.

The Physics and Astronomy Classification Scheme® is designed to assist in the retrieval of information, such as research articles published in archival journals, that has been assembled into various kinds of indexes. These indexes can be, for example: the subject indexes published with each annual or semiannual volume of a journal; cumulative indexes, covering several years of a single journal; compiled subject indexes for many journals taken together; and so forth. Cumulation, either in time over several years or across disciplines published in different journals, is made possible by the use of a common scheme. Many subject indexes are arranged alphabetically. This Classification Scheme, on the other hand, is arranged hierarchically, by subdivision of the whole spectrum of subject matter in physics- and astronomy-related sciences into segments and then repeating the process of subdivision down to four levels. The advantages of a hierarchical scheme over the alphabetical arrangement include: like subjects can be found grouped closely together; and browsing up or down near any entry will reveal closely-related entries.

PACS contains 10 broad categories subdivided into 66 major topics, a detailed acoustics appendix, and an alphabetical index with corresponding PACS codes. This is illustrated in the summary of PACS. Each of the 66 topics is subdivided into specific categories. For example lets consider the broad category called "ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS "

40. ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS.

41. Electromagnetism; electron and ion optics

41.20.-q Applied classical electromagnetism

41.20.Cv Electrostatics; Poisson and Laplace equations, boundary-value problems

41.20.Gz Magnetostatics; magnetic shielding, magnetic induction, boundary-value problems

41.20.Jb Electromagnetic wave propagation; radiowave propagation (for light propagation, see 42.25.Bs; for electromagnetic waves in plasma, see 52.35.Hr; for ionospheric and magnetospheric propagation, see 94.20.Bb and 94.30.Tt)

41.50.+h X-ray beams and x-ray optics (see also 07.85.Fv in instruments)

Pacs codes which are ended with "-" followed by the letter like 41.20.-q are subdiveded into more detailed codes. And codes which are ended with "+" followed by the letter like 41.50 are not.

Both "PACS" and "Physics and Astronomy Classification Scheme" are registered trademarks owned by the American Institute of Physics(AIP). So please if you're mentioning it somethere make a reference to AIP.