The BEP must have been experimenting with this
so called auto-typical
photogravure for some issues only
because in April 1976 (right after the Commercial Aviation issue shown above)
the USPS issued the Chemistry stamp which shows no sign
of any rosette type pattern of screening as far as I can see.
Wow,for sure no
quality control here when it came to centering.US Scott 1685
To me it appears that the screening is partly
composed of rhomboid dots
which is supposed to be a characteristic of EME (Electro Mechanically Etched)
or computer etched instead of the traditional chemically etched.
Was the BEP ahead of other printers in this?