pltrgyst <pltrg...@spamlessxhost.org> wrote in
news:fqi114hfm8of36sa6hme1ka0lmmk19kp1n@4ax.com:

I didn't follow the link, but an 'A' is a first publication stage, 'B'
second, and 'C' third, except that the US doesn't do a third stage, so
doesn't use 'C'. Some other letters are also used, like 'H' for a reissue.
The letter is usually followed by a digit that shows the actual number of
times that particular case has been published.

Older US patents were not published until granted, so regular patents all
had an 'A' without a digit after the number, as that was the only stage of
publication. When publication before grant was introduced that became an
'A1' document, because it was the first publication stage and the first
actual publication, and then the granted patent became a 'B' document as it
was then the second stage, but it is more specifically a 'B2' document if
it follows the 'A1' or a 'B1' document if the 'A1' stage is skipped, either
because it was granted before the 'A1' was due to be published (18 months
after filing) or because there was a non-publication request.