Patent classification systems

There have been many patent classification systems, and any that helpfully classify aero patents in our period are relevant to include here.

International/global systems

• the CPC category system is the most modern and global, started 2010
• the IPC is the predecessor to the CPC, started 1971, per Wang (2018)]]
  • IPC1-7 - an IPC version or variant
  • sometimes there are specific references to the 2006 or other dates of one of these

National systems

• Australian patent classifications
• Austrian patent classifications
• Belgian patent classifications
• British patent classifications
• Canadian patent classifications -- seems to look a lot like the USPC but the history of it is not known yet ; it was used till circa 1989
• French patent classifications -- dated in 50-year groups from 1858-1904 then from 1904-1958
• German patent classifications -- starting 1877-8, had the highest examination standards; until further notice this system was also used in Norway and Finland
• Hungarian patent classifications
• Italian patent classifications
• Norwegian patent classifications
• Swedish patent classifications -- include examinations starting 1884; only US and DE were doing that already
• Swiss patent classifications
• US patent classification systems
  • USPC -- US standards used officially from maybe 1912 till at least 2013, start date uncertain
  • NBER patent classifications - a grouping of the USPC system into larger simpler clusters, used in economics research especially
  • US patent classifications of 1830, 1836, 1867, 1872, 1878, 1899, 1900

Enclosing categories	Techtype
Subcategories	CPC, IPC, IPC1-7, Australian patent classifications, Austrian patent classifications, Belgian patent classifications, British patent classifications, Canadian patent classifications, French patent classifications, German patent classifications, Hungarian patent classifications, Swedish patent classifications, Swiss patent classifications, US patent classification systems, USPC
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