What are .M1, .M2 mempak extensions?

[Legend]

I'm using Nrage's plugin and I'm going to start organizing my mempaks instead of letting the emulator handle it. It doesn't see any of 1964's mpk's because their extension is .M0 instead of .mpk. So fine, I'll change the extension. But I noticed that alot of my games have ALSO another file or two with extensions like .M1 or .M2 or .M3? What could these possibly be????Are these different parts to a single mpk or different mpks or what???

 

[Legend]

Or does anyone simply know which file is the mempak? I'm assuming it the one with .M0 extension.

 

[tailslol]

dunno sorry it can be a mem pack extention to create a bigger extention pack than a real one but its just a suposition