Thanks for the definition. I had looked in a dictionary and the definition was couched in terms of a philosophical theory...it began to sound like quantum mechanics. I get it now. I found some more "knowledge papers" which added to my understanding. I even found a slide show on R-T Timed Loops which has enough volume to be heard.
Just one more point of understanding; I gather that a R-T module on a PC would allow deterministic timed loops to drive multiple cFP units via ethernet connections or a R-T program could be loaded onto a cFP controller which could also run other properly configured cFP controllers/modules without a PC. One advantage would be removing the PC from the actual running of the program; it would then act as a monitor for data queries and a possible location for data downloads. But, some cost could be saved if an embedded R-T controller could be replaced by an ethernet expansion I/O backplane.
The catch is that ethernet is not deterministic.