1 Cent 1979 Regina Doubled Die

I say too shelf like, not because I am an expert but because I was taught

It's MD. It is caused by, in the nanosecond after the strike, the die is a little loose in its holder and the slightly rotates as the dies rises off the planchet. Tightening the holder eliminates the MD. With a good offset seen, one half or so of the letters/digits will show a little shelf or shadow of the strike but, with a smaller movement, it may only affect a small section of the design, more as the distance increases from the center. Looking at the serifs of the letters, you will just see the shadow and not a split serif. A split serif normally means the repunch or double die. MD is not considered a variety, since the movement happened just AFTER the strike, and not part of the actual strike.