A Twill-binding with a 30/20 density (30 vertical threads/cm and 20 horizontal threaads/cm):
The Argentina watermark has multiple Suns + A#1071; since 1922 but there are various versions of it depending on the manufacturers.
When the line of RA is parallel to the direction of paper, we have a parallel watermark, when the line of RA is perpendicular to the direction of paper, we have an orthogonal watermark.
This distinction is vital! I will come back to the UK/Commonwealth watermarks where a watermark seems to be unchanged but in fact two different watermarks had been used.