This bug/feature cropped up in one of my pages when viewed in google chrome so i wrote a test page which looks like this
To cite section 4.10.21.2 of the HTML5 specification:
"If the form has no submit button, then the implicit submission mechanism must just submit the form element from the form element itself."the form element itself."
Therefore I believe Chrome's behaviour to be correct, although I think other browsers do this as well. You can catch/block/process form submission by listening to the "submit" (e.g. to block it) event.BlockquoteBlockquotethe form element itself."