Mouse-centricity (ODF all versions)

Dear all,

18.281 has 

----b
The form:focus-on-click attribute specifies whether a form button
control should grab the focus when it is clicked with the mouse.
----e

* What, in ODF terms, is "the focus"? And what does it mean to "grab"
it? (Note: an editorial note asks this too). A formal terms and
definitions section would be helpful in clarifying such usages.

* How does this sentence apply to a mouse-less environment (e.g. a voice
browser)?

* Is this really only a "should" thing (recommended behaviour?)

- Alex.