Certificat d'addition

Cert d'addition is and was the name in the French patent systems for supplementary patents, also called patents of addition.

They seem to have changed their numbering procedures over time. In an earlier period, certs d'addition don't seem to have their own numbers. Then at some point they start to have their own numbers, but starting from a small number. By 1915 it's easy to tell whether a patent number is an original or a cert d'addition by whether it has a number less than 30,000 or greater than 300,000; there weren't any in between.

If we study here we can find when the procedure change occurred, if it's as simple as just described, a switch from one to another. We'd earlier considered possibilities such as French certificates of addition taking on auxiliary numbers, auxiliary relative to the parent number, that is, and with this auxiliary numerical process re-starting with each year. Now there are indications that this was not the case. Patent FR-1902-323250.862, for instance, indicates that at some point quite close to the turn of the Nineteenth Century the practice may have been adopted.

(Both the parent patent number and the number peculiar to the cert d'addition seem to be universally present on text page 1 within each original, as we get into the Twentieth Century. A number of diagram pages seem to emphasize the number peculiar to the cert d'addition.)

Example: Our evidence doesn't show Patent FR-1894-205155.2 having its own unique official patent number, so we show it with a suffix ".2". It may be that this addition did have a number, and we will find it someday. Or maybe they didn't assign certs d'addition their own numbers at this stage. Later, they did. We can document the cert d'addition numbering procedures as we work them out.