[Tagging] unclear motorway_junctions

[Nathan Edgars II]

So highway=motorway_junction applies to a node, and helps routing
software by giving it the junction number to tell you to exit at.
Presumably said software would assume that if there are three legs at
the intersection, two non-links and one link, movement onto the link
is taking the exit. But this isn't always going to be true; one might
have all legs non-link (a major split signed as an exit from one
route: http://www.openstreetmap.org/?lat=28.85883&lon=-82.09167&zoom=16&layers=M)
or two links (a split at the end of a route:
http://www.openstreetmap.org/?lat=27.89497&lon=-82.50818&zoom=17&layers=M
currently tagged with exit 1A where that side of the split curves away
from the once-proposed extension, but it would more correctly be at
the same place as exit 1B:
http://www.southeastroads.com/blog/fl-618_wb_exit_001b.jpg). Would I
want to use http://wiki.openstreetmap.org/wiki/Relation:destination_sign
for this, or is there a simpler way?