setrans.conf

[Ivan Makale]

I'm studying SELinux and I'd like to find a clear explanation of the 
syntax used in the setrans.conf file. Have anybody a web resource to 
suggest?
So to give an example,

s0-s0:c0.c1023=SystemLow-SystemHigh
s0:c0.c1023=SystemHigh

Is '-' indicating a range between sensitivity levels and the ''.' a 
range between categories? What's the difference between "s0" only and 
"s0-s0"? And so on...
Thank you, Ivan Makale