RE: office-comment Frames / Information Loss (ODF all versions)

["Dennis E. Hamilton" <dennis.hamilton@acm.org>]

I notice that "supports best" is also a problematic determination.

There is something that I notice in all of the statements in the ODF
specification that admonish for preservation.

1. The problem is that there is no distinction between preservation of
untouched material versus situations where (as in the case at hand) touching
the one rendered would prospectively invalidate the others and the processor
might not be able to determine whether that is the case.

2. Also, in the case of unknown/unsupported material, when *anything* is
touched pretty much anywhere, it is not clear whether the
unknown/unsupported material has been invalidated or at least left
inconsistent with the changed material.

It might *not* be the conservative and safe thing to preserve material that
is unsupported/unknown when a derivative ODF document is being produced.

(It might also be valuable to design material that depends on other material
being unchanged to incorporate provisions by which a processor can reliably
detect that a dependency invariant may have been broken.  That takes a
cooperative arrangement of some sort that fails properly when an unaware
party touches the material.)

Also, there are concerns among some implementers about the dangers that
unsupported/unknown components represent with regard to prospects for covert
channels, unintended disclosure, and security/privacy exploits.  The
creation of a digital signature that encompasses unsupported/unknown
material is particularly problematic.

I don't have a prescription for this.  I do think that decontextualized
injunctions to preserve or not preserve are useless.

 - Dennis

This message is my personal observation and any similarity to an official
position of the ODF TC or of OASIS is purely coincidental.  Were there such
an official position, there'd be provision of a link to the official minutes
or other approved document where the official position is expressed.

Dennis E. Hamilton
------------------
NuovoDoc: Design for Document System Interoperability 
mailto:Dennis.Hamilton@acm.org | gsm:+1-206.779.9430 
http://NuovoDoc.com http://ODMA.info/dev/ http://nfoWorks.org  

 

-----Original Message-----
From: Alex Brown [mailto:alexb@griffinbrown.co.uk] 
http://lists.oasis-open.org/archives/office-comment/200903/msg00089.html
Sent: Saturday, March 07, 2009 06:13
To: office-comment@lists.oasis-open.org
Subject: [office-comment] Frames / Information Loss (ODF all versions)

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.

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