How to recognize them and is that all???
The parallel watermark with symmetrical paper wire - English paper papel inglés - direction of paper parallel to the long side of the stamp "M":


The orthogonal watermark with symmetrical paper wire - Dutch paper papel holandés - direction of paper parallel to the long side of the stamp "M":


The orthogonal watermark with symmetrical paper wire - Dutch paper papel holandés - direction of paper parallel to the short side of the stamp "m":


This last version has got the same line of AЯ as the one with parallel paper!
Re-posted as there is no way for me to comment the article in Revista 225 by J.R. Merlo on this subject....
rc2089