Patent classification systems

There have been many patent classification systems, varying over time, and varying between nations in the manner and the timing of their evolutions. To the present-day researcher, working at least largely online, and interested in finding antique patent material, international/global systems are of note in their retroactive projection of later international classifications onto antique, and national, patent material. Contemporary national patent websites, when they exist, vary in their overall quality and in terms of their active interfacing with the below-mentioned internation/global sytems and with the international websites through which we may gain at least a partial overview. All of this affects our manner of gathering data and in some instances it affects the manner in which we ultimately determine the antique patent classifications which were nationally applied.

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
• Dutch patent classifications -- an interesting case in which a late patent office founding led perhaps to an unusually modern-practical "early" national system, also an interesting case in that antique national classifications have been retroactively applied, in the manner of IPC and CPC, and seemingly in the interest of interfacing with these ; in some cases this retroactive application of an antique- and nationally-based classification leads to the inclusion of material likewise antique- and nationally-based material which veers greatly from the actual antique classification system, as such; but yielding material which nevertheless fits the technology being sought ; the antique and national classification being sought is then determined by way of viewing the original, largely by way of Espacenet, after the patent or patents have been found.
• 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, Dutch 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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