My thanks to all those who have made comments about Boole and Boolean logic/searches etc - it's been really interesting! It's fascinating to see how something like algebraic logic has been transformed into standard library and computer practice - to the extent that I, and I'm sure many others, didn't know where it started and with whom. I wonder if there are ways of searching which will be developed? ...Of course there will be; but being no Verne, I have no idea what they'll look like...