Quote from CT10Gov:
I should also point out that all MBS bought by the fed were 'agency' (http://www.newyorkfed.org/markets/ambs/). There's none of that no-doc junk crap in those collateral pools.
Attachment point is the percent loss that a collateral pool must take before the tranche is hit; detachment point is when the tranche is completely gone.
Ah. I had never heard that terminology.