text:object-index (ODF all versions)

In 7.6:

----b
The <text:object-index> element represents an index of the objects in
the current document or chapter. It gathers its entries from the known
object types.
----e

* what are the text entries in an index of object?

* how is this sorted? (we learn earlier indexed are "generally" sorted)

* does this element "represent" such an index, or cause it to be
displayed?

* what does "object" mean here? Does this include (say) "drawing
objects"?

* what are "known" object types?

* what are object "types" in ODF?

This needs an example too, I think.

- Alex.