Thanks for that link, it's a very nice explanantion... (even tho' I have only got half way through.)
I particularly liked the explanation of the operating side of things, especially at 30 mins when they show a live timing graph with the signals aspects overlaid on it. I was familiar with BR train planning graphs in the 1970s and thought that the Swiss way of using printed versions as a driver's timetable in the cab back then was very clever, especially as on single lines with passing places it gave an immediate feel for where other crossing trains were - or should be.
As a live front-line operating tool it is another level of professionalism!