@Miller,
Thanks, Miller. I acknowledged in my next post that counting triglycerides as part of total cholesterol seems to be common after all. Since this is obviously a heuristic formula, you can expect the coefficient in front of the triglyceride level to vary from source to source. From a biochemical point of view it should be zero, because as I said, triglycerides aren't types of cholesterol. They're a different class of substances.
Medical people sometimes use classifications that make no sense biochemically, but work for them in practice. I guess this is one such time.