Unknown marks on a riza which seems from Russia but it isn't

Hi there,
I hope you may help me to recognize the 2 marks (“AT” and “12” in ellipse ) which are on the riza of the “Mother of God” icon you can see in the attached pictures.
As you see, this, in my opinion, beautiful and well made icon should be from Russia but the marks are not the russian ones: moreover, I have not even found my icon within the hundreds of kind of “Mother of God” in Russia. I do not think this is from Greece but maybe it could be from Bulgaria or Romania or… Poland: on the back, written in ink, it is still possible to read “Mater Domini” which is “Mother of God” in latin…
Thanks a lot and kind regards,

That is odd. It does look like it should be from Russia due to the faces of mother and child, as well as the metallic design. Perhaps it was replicated from a Russian design elsewhere. Have you considered areas just outside of Russia?