Whenever a user, a government, a school or a business chooses the format in which to store and exchange its digital documents, it is not merely making a technical decision, but is placing a bet on the kind of digital infrastructure on which it will depend in the future.
In this sense, ODF and OOXML are not two equivalent options on the same shelf, but two radically different solutions: one geared towards a future of openness, interoperability and digital sovereignty, and the other towards a past of defending a vendor’s dominant market position through user lock-in.
ODF: designed to be open and transparent
Open Document Format was conceived from the outset to be an open standard. It was designed and developed by the community under the auspices of OASIS, and subsequently ratified by ISO, to be implemented by anyone, on any platform, without royalties, without hidden dependencies and without the permission of any single company.
These are not trivial technical details, but a statement of political and economic strategy embedded within the format itself.
ODF is based on a clean XML schema, easy to read even by non-technical users and reusable. Colour naming follows standard web conventions, and its architecture reuses components from widely adopted open standards. The format was designed to work within an open and transparent infrastructure, not against it.
When a public administration archives a document in ODF format, it can be certain that any future government, any future open-source or proprietary application, and any future platform will be able to read, manage, process and transform that document, because the format specifications are publicly available, and are clear, complete and free from restrictions.
In this sense, the commitment to ODF is a forward-looking one, because it is in line with the evolution of technologies and infrastructure based on open-source software, and with the European agenda on digital sovereignty.
OOXML: designed to preserve the past
OOXML, or Office Open XML, was not designed for interoperability, but to do something very specific: to encode Microsoft Office’s binary formats in XML in such a way as to allow Microsoft to claim compliance with the standard without relinquishing control over users through lock-in.
This origin story is not ancient history, but dates back to the period between 2006 – purely by coincidence, the year the ODF format was approved by ISO – and 2008, the year of the farcical event known as the Ballot Resolution Meeting which led to the approval of OOXML by ISO, and is written into all versions of the specification.
OOXML Transitional, the variant that virtually all Microsoft Office documents use in practice, and the only one available today, is explicitly defined as a compatibility layer with legacy binary formats (the now-forgotten DOC, XLS and PPT, which were nothing more than the saving of working memory to disk), and contains thousands of undocumented elements, format-specific exceptions, and references to legacy Microsoft systems that no third party can fully replicate.
The specification itself acknowledges that Transitional documents may contain elements whose behaviour is ‘legacy’ and whose correct display requires knowledge of Microsoft’s proprietary systems. In short: to implement OOXML Transitional correctly, one must decode thirty years of Microsoft Office history, something that no one except Microsoft can do, and no one ever will.
In this sense, the choice of OOXML is not a gamble but a backward-looking choice, because the format is only open in appearance – but it takes very little, just a bit of goodwill, to realise that it is completely closed – and was designed to be a lock-in mechanism.
Two completely different standardisation paths
OOXML’s path to ISO ratification is a catalogue of everything that should never happen during a standardisation process, starting with the Fast Track method. One comment was: “It will be truly sad if ISO lowers its standards so far that it will accept this monstrosity”.
Another comment, from a member of the ISO Technical Committee that approved OOXML, sums up the format’s problems: “The trouble with OOXML is not just that the document itself is monstrously huge. The current OOXML format has a number of technical problems which have been listed in detail elsewhere. Another problem is that the specification itself is not written as a standard, but more as the sort of technical documentation you’d expect to find for a commercial product. This will cause serious interoperability problems in practice, and since interoperability is the whole point of a standard, that’s not acceptable”.
The market has confirmed what the standardisation process had sought to conceal: OOXML Transitional never delivered the interoperability it promised, and this is confirmed by content loss, rendering differences and various other incompatibilities between Microsoft Office’s implementation and those of third parties, which are persistent and still documented today. A true standard should be perfectly reproducible by following its specification, and should not require reverse engineering or trial-and-error approaches.
ODF, by contrast, has followed the standard ISO standardisation process, and for this reason it is the format recommended by the EU Interoperability Framework, by the German Deutschland-Stack – which mandates it alongside PDF/UA at all levels of public administration – and by a growing number of national frameworks, which have independently concluded that true interoperability requires a genuinely open standard, one that meets the definition of a standard such as ODF.
ODF is “forward-looking”
A forward-looking format is one that reduces future dependency, not one that reinforces it. It is a format that can be used without requiring knowledge of a single vendor’s proprietary technologies. It is a format that a public administration can confidently hand over to its citizens, its archives and its successors.
ODF meets these criteria. Its architecture is transparent, its schemas are clean and its governance is genuinely open. Its various implementations demonstrate every day that it can be implemented fully and faithfully by projects that are very different from one another, not because they have reverse-engineered it but because the specifications are complete and easily understandable.
A “backward-looking” format, by contrast, is one that ties the future to the commercial strategies of a single vendor. In this sense, OOXML Transitional is an archaeological artefact that preserves the past at the expense of the future. Organisations that adopt it as a standard are betting – or perhaps merely hoping – that Microsoft’s roadmap, Microsoft’s pricing and Microsoft’s platform choices will remain unchanged indefinitely.
It is a risk that no government, business or institution – or indeed any individual concerned about the long-term integrity of their data – should feel comfortable taking.
The problem with “alternatives” that aren’t really alternatives
The OOXML-based lock-in has a second, more subtle dimension – and one that is far more dangerous for users – which deserves to be explained: the role of software that presents itself as an alternative to Microsoft Office, but which uses OOXML as its default native format.
This is a biased technical choice. When an office suite, whether proprietary or “nominally” open source, sets OOXML as the default format for documents, it does not offer a way out of the Microsoft ecosystem, but actually reinforces it. Every OOXML file created by a non-Microsoft application is a file that validates OOXML as a standard, which feeds into Microsoft’s narrative on interoperability and makes migration away from the Microsoft format stack marginally more difficult.
The real alternatives—applications that take interoperability and open standards seriously—use ODF as the default and treat OOXML as a compatibility layer for import/export, not as a native format. The distinction is important: it is the difference between supporting the ecosystem of open formats and entrusting one’s format strategy to Microsoft’s legacy architecture, whilst calling it openness.
Germany has chosen
The German mandate on the Deutschland-Stack is the clearest signal in recent times of the direction European policy is taking. By mandating ODF at all federal, state and municipal levels, Germany has institutionalised what advocates have been saying for at least twenty years: that open standards are a prerequisite for digital sovereignty, not an optional preference.
The mandate is not against Microsoft, but in favour of sovereignty, because it asserts that government documents belong to the state, and not to a single vendor. Citizens’ data must remain readable forever, and cannot in any way be subject to a software licence. Therefore, the document format must allow public administrations to make an independent choice, and to migrate without the format itself posing an obstacle.
The path forward is clear
ODF is the format of digital sovereignty, and of an open, transparent and interoperable public infrastructure. It was designed for a future in which no single vendor can control the documentary level of civilisation.
OOXML is a format closely tied to Microsoft’s corporate history, translated into XML and ratified amid controversy. It was designed to ensure that the future remains compatible with Microsoft’s past, and this future means freedom of choice for governments, organisations, businesses and individuals, and ownership of their documents.