Newport Boy - I copied the ISO sizes off of a fact sheet. Those might have been what fits in the magazine and the printer does handle other sizes. (13" x 40" is mentioned). Sorry I didn't check more closely.

The US convention, as used for engineering drawings, is similar, with an A size being 8.5 x 11. For each increment larger the short dimension is doubled, so:

A = 8.5 x 11
B = 11 x 17
C = 17 x 22
D = 22 x 34
E = 34 x 44 (not used much)

For anything larger you'd go to an "R" with a constant 44 inch top to bottom and multiples of 11 inches for the length. Common lenghts are 77" and 132." For the R sizes it's customary to add about 2" - 3" for "wear strips" all the way around, and some smaller sizes often have some added margin; but that part of it isn't really too standard.

We also see "legal size" at 8.5 x 14, but legal size is illegal for anything submitted to the US Supreme Court, so it's used only by cheap lawyers and real estate agents now.

John