I have coded a structured pattern that should be detecting <input/> elements with an id attribute but no name attribute. All the details are in the image below. There is a regex match on the attribute names that should not match if the 'name' attribute already exists. However, it does not fail, but instead matches an element like <input id="foo" name="foo" />. Also, it does not seem to matter if I toggle the regex between "should" and "should NOT". It matches either way.