[css-flexbox][css-grid] What is "white space"?

Hi,

Both specs contain similar text to define flex items and grid items:

> [...] each contiguous run of text that is directly contained inside a
> flex container is wrapped in an anonymous flex item. However, an
> anonymous flex item that contains only white space is not rendered,
> as if it were display:none.

"white space" is a link to the white-space property:
http://www.w3.org/TR/CSS21/text.html#white-space-prop

What does this mean? Is any of the character mentioned in that section 
considered white space? Or only those collapsed/removed based on the 
inherited value of the white-space property?


If it matches the intended meaning, I suggest linking to chapter 4 
instead: http://www.w3.org/TR/CSS21/syndata.html#whitespace

-- 
Simon Sapin