Some sheets of this issue has missing perforation in one direction on parts of the sheet.
The vertically perforated sheets seem to
a/ have horizontal perforation between rows 2-3, (3-4?), 4-5, 5-6. 
or
b/ have only the top/bottom of the sheet imperforated (50B + 1L)

The horizontally perforated sheets seems to have at least 2 variations as witnessed by the 2L
and the 10L shown here.

Perforated in one direction	+ partial perforation in 2 directions
	R9-10/6-7

missing and misplaced perforation