[ceptimus]

The flaw with the naming arrangement is that it changes from a 'power' series (for the smaller sizes) to a multiplicative one for the larger. I agree that the naming scheme for the larger sizes makes perfect sense - it just doesn't fit well with the naming scheme for the smaller sizes.

In the smaller sizes, the number is a (negative) power of 2: A sheet of An (where n is 0, 1, 2, 3, 4, 5, 6, etc.) has an area of 2-n square metres.

If the same naming system were used for the larger sizes, then a sheet of 2A0 would be called A-1 and a sheet of 4A0 would be A-2, etc.

On the other hand, if we used the 'large' naming scheme throughout then the sheets should be called (in decreasing size order):

4A0, 2A0, A0, 1/2A0, 1/4A0, 1/8A0, 1/16A0, etc. (1/16A0 would be what we call A4)