r00t	=	{HW}{!}
HW	=	{H} {W}
H	=	Hello
W	=	World
Note	=	This shows the mechanics of expansion: Clicking on "Document" launches a parser. The parser looks for a line that begins "r00t=". It takes the right hand part (the part after the "=", e.g., "{HW}"), and treats that as the text of Document. It looks for any "variables" - strings of text bracketed by braces ("{" followed by a "}"). If there are any variables, it "expands" them by looking for a key with a matching name. If it finds a key that matches, it makes the substitution. It repeats until all variables have been substituted or been found not to have matching keys. In the Document view, it returns the text of Document with each substitution marked with the name of the variable (do a mouse-over) and each unmatched variable highlighted in red. Next demo is how to include another file to access its key/values.