Doug Brown wrote:

I really can't see what the problem is, other than aesthetics.**Even*with
the notch as described, and the upright fastened (either lag bolted or
screwed) to the rim joist, you**still*have*a*full*2"*thick*post*supporting
your railing.**This*is*even*if*the*4X4*splits.**I*am*no t*certain*how*much
force would be required to cause a 2" thick post to fail across the grain
but I suspect it would be more than mere leaning against the railing or
post.

It wouldn't be across the grain. it would be with the grain. IOW, the post
might split upwards from the notch.

My original question remains unanswered. Would a bolt/screw/lagbolt through
the post just above the notch resist such splitting? I think it would, but
wondered if others agreed.

--
It's turtles, all the way down