What are you trying to do with them? The mains ones to be concerned with are Cuelists, Overrides, and Chases.
Cuelists are you generic get everything done ones, great for color toggles, scenes, theater cuestacks, song Cuelists.
Overrides are there to take priority over everything, control FX speed, or make a certain scene appear no matter what.
Chases are to make something happen over and over again, easy to use
Timecode cuelists are the same as Cuelists just can use timecode.
Inhibitives act as a grand master for any specific fixtures.
Submaster control
Intensity only! They're great for my
house lighting and key lighting that I want to know for sure will turn on if I turn on that
submaster.
Just start playing with them, you just have to keep in mind that you stack Cuelists and everything to get the looks and control you want. It is a stacking and a priority
system.
For any more M-Series questions, there is a great and active Facebook group.