Below are examples of three different varieties of Subtype A of AMEX printed cancels under the classification scheme used by Henry Tolman in his collection. See the previous post for background. Subtype A includes stamps with the sans-serif 189x format, with the 1 of the 189x year date under the left leg of the X in AM. EX. CO.
Stamp above is classfied as normal, with three rectangular or near rectangular periods in the AM. EX. CO. portion of the cancel.