See chapter 5 of ts.nist.gov/Standards/Conformity/upload/ps20-05.pdf for
(minimum) standard lumber sizes.

Eigenvector wrote:
Is there any type of wood that is sold as per its dimension anymore?

I tried to buy some cedar that was as advertised, nope even something as
simple as a 1x2 cedar strip is actually 5/8x 1 1/2. It sucks because I
have to buy a 1x4 board to fill a 2" gap or actually I have to buy a 2x4
board and rip it 2 ways with a tablesaw to fit a 1x2 gap. This has to
be a ploy to sell more lumber, can't this be attacked as a "truth in
advertising" or false claims angle?