> Can anyone see any reason to keep the ISO code in there?

Frankly, No. Some of you may be too young to remember the era (late 1980s?)
when the Internet was going to switch from IP to ISO protocols any day now.
(That was when that code was put in there.) The only advantage I ever saw
w.r.t. using TP4 over TCP was that, since the checksums were much harder
to calculate, it was much slower and therefore didn't put as heavy a load on a
network:-)

Just my opinion, worth what you paid for it, rick