Regarding the A-variant, Canon Europe has given this reply
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The reason why some media have a Capital “A” (e.g. Canon Photo Pro Premium Matte A) at the end of the naming is as follows.
The prescription or formulation of media sometimes needed to be changed due to unexpected reason such as discontinuation of coating material, or so on after launching printer.
This change sometimes requires new profiles or calibration target although most of the case the difference between old and new media is not so big
CINC would like to differentiate new from old one, therefore, they create new media profile with new naming with “A” at the end of the media name.
This naming convention comes from consumer product group in Tokyo, who developed PRO-1000. Because PRO-2000 & 4000 need to have a consistent naming as PRO-1000, we have some media whose name have “A” at the end.
I would recommend for your customer for those media where a 2nd media with uppercase A at the end exists, to activate that media and to remove the original media in the media file.
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It makes sense for specific papers where coating etc might change over time.
It does not include an explanation to what A types might mean for base paper choices in setting up custom media in MCT. That would be nice to know.