HTML Checking for Large Sites
Rocket Validator integrates the W3C Validator HTML checker into an automated web crawler.
An attribute has been found in an element, where the intended value is missing. A common cause is including the equal sign, but not passing anything after it.
For example:
<!-- This is missing the value for the style attribute, so it's invalid -->
<p style=></p>
<!-- This is explicitly passing a blank string as the value, so it's valid -->
<p style=""></p>