Rotation Number Sequences?

I thought I was a fairly experienced Paladin tank -- I've been tanking for quite some time now and I've been to T5/T6 content on occasion. Then I see others talking about rotations in terms of numbers - i.e. 6969696 or whatever. Now I feel like an ignorant paladin tank. Can someone point me to a reference that explains what these numbers mean so I can feel less like a failure?

Edit: I can accept if I need to be flamed for this one.
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http://www.failsafedesign.com/maintankadin/viewtopic.php?t=13944
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R.I.P. Sanctity Aura, it's Hammer Time

Thanks!!
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