Numbered Headings (ODF all versions)

Dear all,

5.1.6 has:

----b
The <text:number> element contains the text of a formatted number which
is present when numbering is applied to an element.
----e

One of the possible parent elements of this element is <text:h>

How is it possible to tell whether headings (<text:h>) in a document are
to be numbered? (in which case, one assumes, this element will appear in
saved documents?)

Or, put another way, how is "numbering applied to an element" when that
element is <text:h> ?

- Alex.