On Sep 28 2004, 15:52, Steve Thatcher wrote: WITHOUT having to figure out what each sytmbol means in the context of the usage, then it is simply more understandable. If I picked up something that had two binary numbers wiht a PLUS sign inbetween, I would not assume that it meant OR, only if you would dig further does the PLUS sign make sense. If you simply said OR, then there is no confusion and it is self documenting. I think Sellam was trying to make this point with regards to symbology. I don't -- agreed the symbols are to *some* extent arbitrary, but I agree with Dwight. If they're arbitrary, then +/. are just as good as |/&. The symbols Dwight used are part of *the* standard for logic expression in Boolean mathematics, and make good sense if you think about it (or know a little about it). The overloading of multiple context-sensitive meanings for things is common in mathematics, programming, and lots of other places. You just have to learn to live with it. If you learn a new discipline or language, you have to learn the semantics (just as a physicist knows that stress and strain are two different things while the man in the street, having read his OED, "knows" they're the same). Do you expect to pick up a book on some strange programming language or some new science and understand the syntax without some explanation? As for confusing addition and the logical OR function with binary numbers, you don't normally perform logic on binary numbers, only on bits representing truth values. Describing "1011 OR 0101" as part of a logic equation is sloppy; it's actually four put together. And lastly, AND and OR are just two binary logic functions. There are fourteen more, if remember my first year maths, all with ASCII symbols, all of which predate C. I sympathise with those who've not seen it before. It can be hard to understand at first; logic is not common sense. It is, however, logical :-) -- Pete Peter Turnbull Network Manager University of York