Iwire, Thanks, mate!. We have a term over here in New Zealand, (and this is used in a few Non-US countries) it is called Square Millimetres and gives the Cross-sectional Area of a particular wire or cable, based on the size of the individual wires and the number of such wires. Here, the wires number 1,3,7,19, in numbers of strands, as the cables get bigger. That doesn't include CEMPEX flexible Mains conductors that we use inside switch panel enclosures, that may have up to 2000 fine wires, but has the same size as a 1/0 conductor. Different strokes for different folks, you know!.
I believe that the change from the use of M to mean 1000x to the use of K is part of a general trend to use metric prefixes. If CM is circular mil, then is MCM 1000000 circular mils or 1000 circular mils.
The problem is that depending upon where you are coming from, the answer is _clearly_ 1000, unless you come from some place where the answer is _clearly_ 1000000.
In our state DOT we still use "M" gallons for measurement/payment of water to construction contractors. Apparently it continues to confuse some people from what I've heard. I would much rather use K gallons (or circular mils) instead, it seems that a lot more folks understand K = 1,000 from my experience.
No wire bias here- I'm standing on neutral ground.