From 037ebeb6badda0448ef06975064b56ce572cee20 Mon Sep 17 00:00:00 2001
From: "Michael[tm] Smith" hidden attribute specified.
Palpable content makes an element non-empty by providing either
+ some descendant non-empty text, or else something users can
+ hear (audio elements) or view (video or img or
+ canvas elements) or otherwise interact with (for example, interactive form
+ controls).
This requirement is not a hard requirement, however, as there are many cases where an element can be empty legitimately, for example when it is used as a placeholder which will later be filled in by a script, or when the element is part of a template and would on most pages be filled in but