Oral Salt consumption during exercise

I recently became aware of several athletes consuming salt tablets during Ironman events to replace sodium lost by sweating during exercise. It has always been my understanding that actual oral salt supplementation was an archaic regime that was discontinued many years ago, and came from the early days of marathon and ultra-marathon running. This prompted me into doing research into the current and up to date scientific position on sodium supplementation during ultra racing. The major problem in finding a definitive conclusion is that there is so much conflicting information. Therefore, I focussed on athletic journals, creditable medical articles and scientific research, ignoring anecdotes