[qohen]

From https://en.wikipedia.org/wiki/Submarine_patent

A submarine patent is a patent whose issuance and publication are intentionally delayed by the applicant for a long time, such as several years.[1][2][3] This strategy requires a patent system where, first, patent applications are not published, and, second, patent term is measured from grant date, not from priority/filing date. In the United States, patent applications filed before November 2000 were not published and remained secret until they were granted. Analogous to a submarine, therefore, submarine patents could stay "under water" for long periods until they "emerged" and surprised the relevant market.