Older patent data that is obtained directly from the patent offices’ often lacks information in the application date/publication date field respectively. This data often comes from the DOCDB database and pre-dates a largely unified patent regulatory system; the corresponding paper applications had no required or set fields for the inventor to indicate important dates.
Upon further inspection of these patent documents, the general date of application can usually be found somewhere within the abstract:
Eg. "135,411. Frost, G. A. April 1, 1919. Packing garters.-A container for a pair of men's garters consists of..."
DOCDB draws together bibliographic patent documents from 90+ countries globally; extending as far as the 1830s. With this in mind, users will notice regular additions to the fields which need to be manually completed by extracting the right data from the written content of early historical patents.