Plate/Electro layouts and numbering.
A total of 20 printing 'plates' were produced from this die.
From the printer's perspective these plates were numbered sequentially. 1 -> 20.
From the philatelists perspective these are plates 1..5 and electros 6..20.
Initially supplied with blank gutters ('plates' 1 to 9), due to the security risk, they were later inscribed with single lines (electros 10 to 16), followed by double lines (electros 17 to 20).
Perforation pips were in the now standardised 640on position above and below central gutters for all 'plates' (including 320on copper).
As such, these pips can be collected with 0, 1, or 2 line gutters.
On one electro, the imprint is missing from one corner block of a po sheet.
Imprints were always in the traditional left corner of each pane.
The first plates produced for Die2 were 320on. These had plate numbers 1 or 2 in the corners with no gutter lines.
All following plates shifted the position of the plate numbers to the central gutters.
The next 3 plates (#'s 3, 4 & 5) were also 320on copper plates, again with no gutters and with the traditional flush perforations associated with this plate type (but moved plate #'s)
Finally, a steel 640on negative master plate was produced, from which four positive altos were (eventually) made.
The first alto had no gutter lines and produced four nickel electros 6 to 9. The 9th electro was never used.
Altos 2 and 3 had a single line gutter, and produced electros 10 to 16
Alto 4 had a double line gutter producing 4 electros, 17->20. Only 18 and 20 were used.
Note that the master plate, not the alto, had the gutter lines added to it, to produce the alto,,, that produced the electros with that characteristic.
copies are known with “4” and “- 4 -“ with the perfs flush along top, OR a few are known like this with the 1 perf extension above. The only 2d plate this is known for