I recently obtained this registered envelope and I am trying to figure out which one it is. It has a type III indicia and is 228mm x 101mm in size. According to Shoemaker's book, there are only two envelopes it could be; #16 (Rogers #10) or #17. #16 has a green Indicia but this is obviously not green. #17 has a gray indicia, but this one seems faded. Could be blue or gray. The one thing to notice is the font of the instructions. It is Roman (with serif). This is unlisted in Shoemaker. Am I missing something? Any help would be appreciated.