nber category 2 Computers & Communications subcat 21 Communications

uspto classes
178 Telegraphy
333 Wave Transmission Lines and Networks
340 Communications: Electrical
342 Communications: Directive Radio Wave Systems and Devices (e.g., Radar, Radio Navigation)
343 Communications: Radio Wave Antennas
358 Facsimile and Static Presentation Processing
367 Communications, Electrical: Acoustic Wave Systems and Devices
370 Multiplex Communications
375 Pulse or Digital Communications
379 Telephonic Communications
385 Optical Waveguides
455 Telecommunications

Historic patent counts for subcat 21

uspto search in the 1790 to present database

ccl/178/$ OR ccl/333/$ OR ccl/340/$ OR ccl/342/$ OR ccl/343/$ OR ccl/358/$ OR ccl/367/$ OR ccl/370/$ OR ccl/375/$ OR ccl/379/$ OR ccl/385/$ OR ccl/455/$

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