A day off every other week. Typical work week is 40 hrs/week. With 9/80, you split 2 weeks of work over 9 days and take the 10th off.
Exactly - a friend of mine had that at Chevron. In addition to the obvious benefits, she also felt more productive the Fridays she was there since the other half of the office was out.
Thanks for the explain action - we call this a nine day fortnight here :)