To ellipsis or not to ellipsis, that is the question.

I’ll bet you have always been asking yourself when is it proper to use an ellipsis. No? You mean I’m the only one? Hope you’re laughing because I am, but probably not why you think. I still have a pinched nerve that requires me to lie flat for a while every day and today I was doing so watching the run up to Super Bowl LI. Picture that, watching super bowl activities and reading the Chicago Manual of Style! Yes, I said the Chicago Manual of Style, or the CMOS as my editors call it. I was bored. And, I was trying to figure out why my editors were doing what they were doing to my manuscripts.
But wait a minute. For some of us who are past naval aviators, this picture isn’t entirely unfamiliar. Around the squadrons I was in there was a common saying: “If you can’t get to sleep, pick up your NATOPS manual and start reading. Just don’t let the book hit you in the forehead.”
NATOPS is short for Naval Air Training and Operating Procedures Standardization. There is a different manual for each kind of aircraft in the Navy inventory. Usually it is thick and heavy with a blue cover. It tells you everything you need to know about operating and understanding the aircraft you fly. And, you get tested on it all too often. I hated NATOPS tests!
So how did I get from ellipsis to NATOPS? Good question. Trying to understand all the rules of published works is like learning about and understanding an aircraft you need to fly — except you don’t die if you fail. But, the CMOS is heavy and can leave a nasty knot on your head if you let it hit you as you fall asleep.
My editors (all 2 of them) have been browbeating me to learn how and when to use the ellipsis (…) in my manuscripts. My pages look like they are blood stained and I’m not sure I’ve got it right yet. It seems that I have been using ellipses exclusively and not knowing when to use an em dash (—) instead. Confused? So am I.
Basically, ellipses are used to indicate a thought that trails off. Em-dashes are used to set off an amplifying or explanatory element.
Oops, the CMOS just hit me in the head! Better get back to the super bowl.
Let me know if you have a sure-fire way to use these correctly. My editors will appreciate it!