http://www.worldofcoins.eu/forum/index.php?action=post;topic=5397.0;last_msg=341792
The WorldofCoins article has inspired this documentation, where it clearly says, thet the M is not a mint mark, but on the other hand the spokeswoman of the Tallinn mint is not sure, what it is either.
The CR is issued, with the please to the referent, to take the references to the M as mint, out of the article. I hope you all agree after having read the WoC posting?