Cuba Satellites And Rockets: Scribbles?

This is a low value item (Scott 859-862 block, issued October 15, 1964), but it has some interesting wording in the selvage. The plate block number may normally be seen near here, but it looks like a listing of the two different greens that were used on this block, plus there is some red and grey lettering. The two shades of green, and the grey appear on the stamps, but not the red. Any idea what this really indicates?

Opinion.
Marginal Markings.
Indications of Instructions during printing.
Seems to indicate "Add claro verde" regarding the green.

Alas, I do not have the full sheets, only the blocks of 6.
I recall similar notations / scribbles on the selvedge of Hungary sheets.
last sheet I have with selvedge markings is Cuba 1960 with "William Soler" emblem.