I've just started at a place that uses a lot of Tcl for embedded scripting and customisation, and I've never used it before so this was very handy.

That said, the document needs work - the syntax highlighting got very confused at some point, and a bunch of the lines are much longer than the width of the document, and don't wrap.

Tcl looks like a nice little language that makes it really easy to write really horrible code. Probably with some discipline you could keep it tidy and comprehensible though.