Mach2

Imserv is where I got the probe. Having looked all through their web
site, I don't understand the difference in Mach2,3, and 4. Mach2 seems
to be the cam/controll software, and mach3 some sort of add on for
design purpose? I didn't see anything about mach4 but I've seen
references to it elsewhere. If they're just updated versions of the
same thing, I'd like to get the latest, but they don't look to me to be
that. Anybody else know?

Thanks
Nathan