Chuck wrote:
Linear, yes... bi-directional? Not as I see
it... and leaves one wondering why NEC3
is available only to government entities
and contractors...
. . .

It's not clear why you have a problem with NEC-3 when it was superceded
long ago by more-advanced NEC-4. NEC-4 can be purchased by nearly
anyone, as a little web research would have quickly revealed. Yes, even
you can buy NEC-4. But alas, it also doesn't take into account magical
phenomena.

Roy Lewallen, W7EL