I wanted to explain in the “Photics Web Guide” that JavaScript should not be added below the closing body tag. Yet, depending on the web browser, this might still work. So, how I do I let the reader know that this not the proper way to do things — even though it might still work?!
Ah, Tumult Whisk! 
It has W3C-based validation.
Would it show the problem? 
It did show the error… it was “fatal” …ha ha ha! 
Looks like you're in the book…
