There has been quite a lot of hubbub recently about ODF conformance, in particular about how conformance to the forthcoming ODF 1.2 specification should be defined.
A New Conformance Clause
Earlier versions of ODF (including ISO/IEC 26300) already defined conformance - it was simply a question of obeying the schema. So in ODF 1.1, for example, we had this text:
Conforming applications [...] shall read documents that are valid against the OpenDocument schema if all foreign elements and attributes are removed before validation takes place [...] (1.5)
and that was the simple essence of ODF conformance.
This is now up for reconsideration. The impetus for altering the existing conformance criteria appears to have come from a change in OASIS's procedures, which now require that specifications have “a set of numbered conformance clauses”, a requirement which seems sensible enough.
However, the freshly-drafted proposal which the OASIS TC has been considering goes further than just introducing numbered clauses: it now defines two categories of conformance:
- “Conforming OpenDocument Document” conformance
- “Conforming OpenDocument Extended Document” conformance
as shorthand, we might like to characterise these as the “pure” and “buggered-up” versions of ODF respectively.
The difference is that the “pure” version now forbids the use of foreign elements and attributes (i.e. those not declared by the ODF schema), while the “buggered-up” version permits them.
Ructions
The proposal caused much debate. In support of the new conformance clause, IBM's Rob Weir described foreign elements (formerly so welcome in ODF) as proprietary extensions that are “evil” and as a “nuclear death ray gun”. Questioning the proposal, KOffice's Thomas Zander wrote that he was “worried that we are trying to remove a core feature that I depend on in both KOffice and Qt”. Meanwhile Microsoft's Doug Mahugh made a counter-proposal suggesting that ODF might adopt the Markup Compatibility and Extensibility mechanisms from ISO/IEC 29500 (OOXML).
Things came to a head in a 9-2-2 split vote last week which saw the new conformance text adopted in the new ODF committee specification by will of the majority. Following this there was some traffic in the blogosphere with IBM's Rob Weir commenting and Microsoft's Doug Mahugh counter-commenting on the vote and the circumstances surrounding it.
Shadow Play
What is to be made of all this? Maybe Sun, whose corporate memory still smarts from Microsoft's “extend and embrace” Java attempts, thinks this is a way to prevent a repeat of similar stunts for ODF. Or perhaps this is a way to carve out a niche for OpenOffice to enjoy “pure” status while competitor applications are relegated to the “buggered-up” bin. Maybe it is envisaged that governments might be encouraged to procure only systems that deal in “pure” ODF. Maybe foreign elements really are the harbinger of nuclear death.
Who knows?
Whatever the reasons behind the reasons, there is clearly an “absent presence" in all these discussions: Microsoft Office. And in particular the forthcoming Microsoft Office 2007 SP2 with its ODF support. It is never mentioned, except in an occasional nudge-nudge wink-wink sort of way.
This controvery is most bemusing. This is in part because the “Microsoft factor” appears not to be a factor anyway, since MS Office will (we are told) not use foreign elements for its ODF 1.1 support. But the main reason why this is bemusing is that this discussion (whether or not to permit foreign elements) is completely unreal. There seems to be an assumption that it matters – that conformance as defined in the ODF spec means something important when it comes to real users, real procurement, real development or real interoperability.
It doesn't mean anything real - and here's why...
Making an ODF-conformant Office Application
Let us consider the procurement rules of an imaginary country (Vulgaria, say). Let us further imagine that Vulgaria's government wants to standardize on using ODF for all its many departments. After many hours of meetings, and the expenditure of many Vulgarian Dollars on consultancy fees, the decision is finally made and an official draws up procurement rules to stipulate this:
Any office application software procured by the Government of Vulgaria must support ODF (ISO/IEC 26300), and must conform to the 'pure' conformance class defined in clause x.y of that Standard, reading and emitting only ODF documents that are so conformant".
Sorted, they think.
Now imagine a software company that has its eye on making a big sale of software licenses to Vulgaria. Unfortunately, its office application does not meet the ODF conformance criterion set out by the procurement officer. The marketing department is duly sad. But one day a bright young developer gets to hear of the problem and proposes a solution. He boldy proclaims “I can make our format ODF-conformant today!”, and proceeds to show how.
First he gets a template ODF document, like this:
<?xml version="1.0" encoding="UTF-8"?>
<office:document-content
xmlns:office="urn:oasis:names:tc:opendocument:xmlns:office:1.0"
xmlns:text="urn:oasis:names:tc:opendocument:xmlns:text:1.0"
office:version="1.0">
<office:body>
<office:text>
<text:p></text:p>
</office:text>
</office:body>
</office:document-content>
This document (he points out) meets the “pure” conformance criteria. Our young hacker then does a curious thing: he takes an existing (non-ODF) file from their office software, BASE-64 encodes it, and inserts the resulting text string into the element in the template document.
<?xml version="1.0" encoding="UTF-8"?>
<office:document-content
xmlns:office="urn:oasis:names:tc:opendocument:xmlns:office:1.0"
xmlns:text="urn:oasis:names:tc:opendocument:xmlns:text:1.0"
office:version="1.0">
<office:body>
<office:text>
<text:p><!-- several MBs of BASE-64 encoded content here --></text:p>
</office:text>
</office:body>
</office:document-content>
There, he proudly proclaims. All we need to do it to wrap our current documents with the ODF wrapper when we save, and unwrap when we load – I can have a fresh build for you tomorrow.
The rest of the story is not so happy: the software company makes the sale and the government of Vulgaria finds after installation that none of the files from it will interoperate with any other ODF files from other sources, despite the software company having met its procurement rules to the letter.
Far fetched?
Okay, that story makes an extreme example – but it neverthess illustrates the point. It is possible for a smart developer to represent pretty much anything as a “pure” ODF document; any differences and incompatibilities can ever-so-easily be shoehorned into conformant ODF documents. That some software deals only in such pure ODF means precisely zero in the real world of interoperability.
The central consideration here is that ODF conformance only ever was (and is only projected to be) stated in terms of XML, and XML is (in)famously “all syntax and no semantics”. The semantics of an ODF document (broadly, all the narrative text in the specification) play no part in conformance can remain unimplemented in a conformant processor. An ODF developer can safely use just the schema and never read much else. All those descriptions of element behaviour can be ignored for the purposes of achieving ODF conformance. [N.B. mistakes in this para corrected following comment from Rob Weir, below]
So my question is: what is the current debate on ODF conformance really about? It looks to me like mis-directed effort.
What ODF might usefully do is to look at the “application description” feature introduced into OOXML. This describes several types of applications, including a type called “full”. Such applications have “a semantic understanding of every feature within [their] conformance class”, and
“Semantic understanding” is to be interpreted that an application shall treat the information in Office Open XML documents in a manner consistent with the semantic definitions given in this Specification.
In other words, it is possible to specify in OOXML procurement that the processor should heed the narrative description within that Standard (not just the XML grammar). ODF currently lacks this. In my view if there is to be any connection between a definition of ODF conformance and the experience of users in the real world, then something like OOXML's “application description” feature is urgently needed. And it might be better done now, than hastily inserted during a JTC 1 BRM ...