Hi. Got this Austrian stamps and noticed one number wrongly printed. Was that common mistake, does that mean all series were facing same mistake? How can something like that happen during production? Thanks
<I have that same stamp, with inverted 9> It's not an "inverted 9" An inverted 9 would simply be a 6, but this number looks like a 6 that has been reversed right to left, ie a mirror image, so the number has been both inverted AND flipped over. Since engravers have to do all their work in reverse when making printing plates, possibly he/they (O. Zeiller and A. Nefe) just got confused here?