In my country (Paraguay) traditional formats were U.S. Letter and "Oficio" (which I shall explain). Now we are slowly transitioning to ISO paper sizes so A4 size is becoming common and widespread. In my case (as an official translator) I have standardized all my practice to A4 sizes.

Now, a holdout is the "Oficio" size, which created a lot of problems for us. This size is usually described in printer drivers as Fanfold or Long Bond, and it is very similar to U.S. Legal size, but one inch shorter in its length (8.5 × 13 in, 216 × 330 mm). South American paper mills often call it "Oficio 2". This was, and still is in many regards, the required format for all official bureaucratic and court paperwork.

This created a lot of trouble for us because in most Spanish localizations companies (example: Microsoft in MS Office) simply translated the "Legal" paper size as "Oficio". Then every secretary and clerk here selected it believing it is "our" Oficio, only to find that text was cropped at the bottom because that "Oficio" was in fact one inch longer than our format. This led to all kinds of manual (mis)formatting.

I think this format had a German origin and came to us through old Spanish practices, but I can't be sure.

Again, thankfully this is becoming a thing of the past since A4 is slowly becoming the standard...

EDIT: That paper size is also known as "US Government Legal" and "Foolscap" and according to Wikipedia is still in use in various parts of the world.