> 94-XX Information and communication, circuits

94-00 General reference works (handbooks, dictionaries, bibliographies, etc.)	94-01 Instructional exposition (textbooks, tutorial papers, etc.)	94-02 Research exposition (monographs, survey articles)
94-03 Historical (must also be assigned at least one classification number from Section 01)	94-04 Explicit machine computation and programs (not the theory of computation or programming)	94-06 Proceedings, conferences, collections, etc.
94-99 Information and communication, circuits (not classified at a more specific level)	94AXX Communication, information	94BXX Theory of error-correcting codes and error-detecting codes
94CXX Circuits, networks	94D05 Fuzzy sets and logic (in connection with questions of Section 94)

94-XX Information and communication, circuits