Frames / Information Loss (ODF all versions)

["Alex Brown" <alexb@griffinbrown.co.uk>]

Dear all,

In 9.4 we learn about frames.

We are told first "[a]n application may choose the representation that
it supports best".

Then we are told:

----b
The order of content elements dictates the document author's preference
for rendering, with the first child element being the most preferred.
That means that applications should render the first child element that
it supports.
----e

Are not these two statements in conflict?

Later we are told:

----b
Application [sic] may preserve the content elements they don't render. 
----e

So, an application only "may" preserve unused content.

Why is an application free to discard information? In the case a variant
implementation is used to support accessibility (say it is a transcript
of a video), is it really okay for that information to be dumped? In
general, how can an application safely dump anything -- since it may in
fact be vital to the document in some way ...

- Alex.