I find this dot on the 20pNGR with upper left corner reworked plus two top cotton bulbs joined, and on the 20pNOP with the two top cotton bulbs joined. These varieties all share a common dot in the same place for the inner frame that I find minus the 20pNGR and 20pNOP additional features on two earlier issues: the 20p1E4 of 1940 and the 20pCL1 of 1943-the early clay printing.
The common dot is found earliest on the 20p1E4 of 1940.
20pCL1, clay paper of 1943.
Upper left stamp.
