Originally Posted by LuCst
We have some international D-Areas that border us and to those we have a blanket 2.5NM radar reparation in the LOAs ...
As whowhywhen says, 2.5 mile buffer works ok if you know that traffic inside the reserved area will also stay at least 2.5 miles from the edge and I think Doc 4444 assumes that traffic on both sides are under positive radar control (and that the standard radar separation is applicable).