I have a nice pic somewhere, but I can't find it.
Basically, like this:
Very early magazines had no caliber marking on them, but you aren't likely to see them.
Pre-ban - at the top of the magazine where it states the caliber - the caliber marking is midways between the very top of the mag and the top witness holes.
Ban - hi-caps had the caliber markind moved up high, and the "LEO only" marking was put in it's place.
Ban - lo-caps had of course, only 10 rounds or less.
After ban - the caliber marking was left up high, with no "LEO" marking in the middle.
Get it?