Complicated question, and I only have part of the answer. These codes probably only apply to certain categories of publications. So you should apply a sanity check to any conclusions. The letter at the end (the R) is a date code. If there is a number after the letter (the 2) it indicates a revision of the brochure and I think it MAY be from a date later than the code.
For US brochures, A was 1911 through Z in 1936. AA was used in '37 through NN in '50. Then they started over with A in '51. If used, O was used in part of '64. Q and V may have been skipped putting W in '69 or '70. Some combination of X, Y and Z were used in maybe '70 and '71. A was used again in '72. Don't know what skips happened after that.
Canadian publications started with A in '46 with Z in '71. They started over again with A in '72.
So if you have a USA brochure, it is from '65 of maybe a bit later. If it is Canadian, it is '63.
