lucy24 - 10:30 pm on Jul 23, 2013 (gmt 0)
I happened to be reading this bit of the CSS spec just a few days ago, so let me give the Horse's Mouth version.
http://www.w3.org/TR/CSS2/visuren.html#propdef-display (auto-linking intentionally disabled)
This value causes an element to not appear in the formatting structure (i.e., in visual media the element generates no boxes and has no effect on layout). Descendant elements do not generate any boxes either; the element and its content are removed from the formatting structure entirely. This behavior cannot be overridden by setting the 'display' property on the descendants.
That's the 2.1 wording; 3 is almost identical.