10 	< 0 or > 10, (outside the range of {0 .. 10})
10: 	< 10, (outside {10 .. ∞})
~:10 	> 10, (outside the range of {-∞ .. 10})
10:20 	< 10 or > 20, (outside the range of {10 .. 20})
@10:20 	≥ 10 and ≤ 20, (inside the range of {10 .. 20})

http://www.techadre.com/content/nagios-thresholds-ranges