Techtypes

Patents are classified by official patent agencies and we can stretch the category systems to other patents which were not originally covered by that category system. Conceivably other data items like publication, aircraft, firms, and inventors can also be classified by the tech type expertise.

There are at least six techtype category systems in this Inventing aviation wiki: CPC, IPC, USPC, the historic French patent classifications, and the historic German patent classifications. in practice the most relevant one is the CPC -- it is modern, detailed, and used cross-nationally. Some historic patents have been assigned CPC codes, possibly by the patent agencies or WIPO. We can assign others. Some cases may be hard to classify.

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