In a nutshell, the principle is that if the final check was being 
done at the last vet check on the trail (the horse still had some 
more miles to go), would he be allowed to continue?  If the answer is 
yes, the horse has qualified for completion.  If the answer is no, 
the horse is disqualified and does not get a completion.
"Fit to continue" applies to the full examination, metabolic as well as 
soundness.
The examining vet is allowed to take into consideration that there is
no safety hazard regarding the horse going into inaccessable country,
and should not pull horses for ordinary muscle soreness or stiffness.
That is, at a vet check on the trail the decision in a marginal case
must be on the side of safety (pull), where at the final check in a
marginal case the decision should be on the side of completion.
As this exam can be done anytime within one hour of finishing (for 
rides 50 miles and up), it is to the rider's advantage to present the 
horse as soon as possible -- which favors proper pacing as well as 
good recoveries.
--Joe Long Rainbow Connection Arabians PC/LAN Manager home of Kahlil Khai Calhoun Community College 11,450 miles completed jlong@hiwaay.net