It will help in our programming to think in terms of Trains. A train has an engine...connected to the engine are cars...in those cars are boxes...and within those boxes are items....or if you like each car has people in them...and each of those people have a name. I will use standard notation now and the dollar sign is to be read variable. So then [Train] = $engine AND $Car AND $Box AND $Item. One of the true beauties of programming is this...there can be any number of trains...with engines of any sort...with any number of cars...with any number of boxes containing any item that you assign...you can have any variable that you choose...and you can assign its' value as anything...anything at all. Beautiful. Variable and Assignment.
