disk identifier - disk1s2 - what does the "s" stand for?

[LeeTom]

Hello - I just got an insatiable curiosity to understand Mac OS X's disk identifying convention. I know the first disk in a system is "disk1", and the first usable partition is disk1s2. I'm assuming that disk1s1 holds partition information (the partition map maybe?) and that's why the first usable disk is "s2", but my question is pretty simple:

WHAT DOES THE "s" STAND FOR?!

Thank!
Lee Tom

 

[cb31]

slice

 

[tkermit]

Seems to be a term carried over from FreeBSD

 

[Ganesha]

slice

It used to mean only slice, but now it can also mean session. So you can end up with a valid disk identifier if the form of diskAsBsC (where A is device number, B is the session number, and C is the slice)