I continue to form a test beginner's collection to show that despite being a complex series, this issue can be collected by novices. I recently received this envelope, and I show here how these stamps get miss-classified today.
All of these are supposed to be wavy rays watermark stamps, 1E or 1L by my scheme. This is what I found:
1E1, 1935 and 1936
1E3, 1939; and I am still not clear if the 5c typographed is 1E1 or 1E3, as my study is not complete.
2D, straight rays, diffused, somewhat rare.
NGR, unwatermarked grid, of varying thicknesses as can be seen from the poor perforations.
The 20 pesos unwatermarked opaque, 20pNOP, which I find used in the mid 1950s even though most NOPs circulated in 1948.
2C, straight rays, clear and bright white paper.
1L1, 1951 wavy rays
and 1L2, 1950s wavy rays with gigantic RA in the watermark.