If you are referring to Pechorins site its because they have an automatic blocking system of so called "double meaning" words when many of the ones they block doesnt actually have any double meaning, and its because of this ridiculous system that you no doubt will get "illegal" or some other message appearing on your screen when you try to post a reply. You will have to go over whatever you wrote and either remove or substitute suspect words for others, for example a standard engineers "S" sheet has to be called engineering manual, as the full meaning of "S" will be blocked. This by the way only happens when using "reply" and not when posting a new message, so either post whatever you replied as a new message of keep altering things and try sending until you get it correct. I frequently have to alter my technical replies to suit this auto blocker.