This is a quote of my post #9:
Originally Posted by krisb1981
"Mechanical compensation, cams. "Auto" means auto diaphragm, it stops down when you take the picture and opens back to max. aperture for viewing and focussing, they all said "auto", standards, wideangles, etc. Yours, if it is indeed the 'K' version, does not have a compensating diaphragm and does not focus to 1:1 without an extension tube. I have the identical lens, there are two ratio scales - one from infinity to 1/2 lifesize, and one from 1/2 lifesize to 1/1 lifesize for use with the tube. "
As I mentioned, all (and more) of this information is available at the Mir site I linked you to.
There is no 'K' mark on the lens.