I think I need to work on this article and make it easier for the new guys to read. I just finished recording an intermediate course on machining centres and my head was still in that.
What do you think?
http://gcodetutor.com/cnc-machine-training/cnc-g-codes.html
I can follow and understand that, good write up, thank you!
@Robert_Hogstedt thats good, thank you for letting me know. I’ve a spreadsheet with another 10 articles I want to write. I Need to get busy lol
The G20, G21 part has the wrong title, and the image has G00 in it instead of G20.
Oh wow! Lol thank you. I will correct that right now.
@Daid_Braam I can’t believe I didn’t notice that! Thank you so much. Its all fixed
Another thing, G04, according to my info, it takes P as time to sleep, not X. https://www.tormach.com/g04.html
X might be some specific addition (like I’ve seen S for milliseconds in 3D printers)
P is used on a lot of routers. Most fanuc Lathes use X and defined in milliseconds. I’ve not tried with using P on Lathes but I expect it would work.
I will add that to the article. Thanks.
There is a mistake on Tormach too 
he has giving P a value of 1 for one second. I’ve never seen a machine that doesn’t define that in milliseconds.
Well, I think there are as many dialects as there are controllers. (My main area of expertise is 3D printers, which has a lot of differences with milling gcode)
Yes your right. I made sure I explained on my courses that Gcodes, Mcodes etc made be different and to check your manual. General guides that is not aimed at one control are great and all but it can never be more than a general guide.