Difference between ISO_expand_a1 and ISO_a1 paper size options?

Question

Im exporting a number for cad pdfs (not graphic design i know, but the paper sizes are still relivant) ive been given a couple of options, either ISO_expand_A1 or ISO_A1 they from the mm length and width they seem the same.

What is it that makes them different ?

Answer 1

This is a guess, but it may relate to German ISO extensions:

DIN 476 provides an extension to formats larger than A0, denoted by a prefix factor. In particular, it lists the two formats 2A0, which is twice the area of A0, and 4A0, which is four times A0...DIN 476 also specifies slightly tighter tolerances...

Then in your CAD app's paper size data model:

• 'ISO..." might contain all ISO sizes

• 'ISO_expand...' might include all ISO sizes with DIN 476 tolerance specs + DIN 476 sizes

The tolerance part is probably only relevant when it comes to physical printing, though.