Digital sovereignty is usually discussed in terms of where servers are located and which company holds the contract. Both matter less than the format in which documents are written.

A document is not a piece of paper

The habit of thinking of a digital document as a sheet of paper is understandable and wrong. A sheet of paper carries its own content. Anyone who can read the language can read the page, with no equipment, no permission and no intermediary. A digital document carries no content at all until software interprets it. The file is a set of instructions, and what appears on screen is the result of a program executing those instructions. Change the program and the result may change with it.

This is why documents produced in one application so often look wrong in another: bullet points shift, tables lose their proportions, headings render differently. The content is present. The document, strictly speaking, is not.

The format is the specification that tells software how to perform that interpretation. Whoever controls the format therefore controls what the document means, how faithfully it can be reproduced, and for how long.

What makes a format open

Openness is not a marketing description. It has established criteria, set out in instruments such as the Open Definition and the European Interoperability Framework, and used by public administrations to assess formats for procurement. Four conditions matter most.

The specification must be published in full and freely available. Nobody should need a licence, a fee or a patent settlement to implement it. The format must be usable by anyone for any purpose, without discrimination between users, applications or business models. And it must be governed by a body independent of any single vendor, so that future versions are decided in public rather than in a company’s product roadmap.

These conditions exist for a practical reason. They are what guarantees that a document written today can still be opened in thirty years by software nobody has yet written.

ODF meets these conditions

The Open Document Format was developed in the open under OASIS, the international standards consortium, and became an OASIS standard in 2005. It cleared its Draft International Standard ballot at ISO/IEC JTC 1/SC 34 in May 2006 with unanimous approval and was published as ISO/IEC 26300 that November. The specification is public, royalty-free, versioned, and maintained by a technical committee whose work is a matter of record. Version 1.4 was approved by OASIS in December 2025.

ODF is not the LibreOffice format. It is implemented by a range of applications from different suppliers, and any developer may implement it without asking anyone. LibreOffice uses it natively, which is a consequence of the format’s openness rather than a claim of ownership over it.

OOXML does not

OOXML, the format underlying DOCX, XLSX and PPTX files, carries an ISO number. It was granted one in 2008 through a fast-track procedure whose conduct is now part of the documented history of standards governance.

The number has not produced the effects a standard is meant to produce. The specification runs to several thousand pages, which discourages implementation. It exists in two conformance classes: a Strict variant, which other developers could reasonably support, and a Transitional variant, which preserves legacy behaviours and is what Microsoft Office writes by default. The variant in daily use by hundreds of millions of people is therefore the one that only its originator implements completely. The cleaner variant that competitors could support is largely unused, and has even disappeared from some versions.

A specification that a single implementation alone can satisfy is, in functional terms, a proprietary format with a standardisation certificate attached. This is not an accusation of bad faith. It is a description of what the format does regardless of anyone’s intentions, and it is the reason the distinction is structural rather than moral.

Why this decision comes first

An organisation that adopts a European cloud provider, negotiates strong contractual protections and hosts everything within its own jurisdiction has achieved nothing for sovereignty if its documents remain in a format only one foreign supplier can read correctly. Server location, hosting jurisdiction and procurement clauses are all downstream of the format decision. An organisation that cannot open its own archives without a supplier’s permission is not sovereign over them, wherever those archives happen to be stored.

The exposure grows with time. An individual with a distorted layout has an inconvenience. A ministry holding two decades of legislative drafts, land registries and court records in a format it cannot independently interpret has delegated custody of the public record to a private company, and cannot withdraw that delegation without converting everything it owns.

Who has already acted

Germany’s Deutschland-Stack, the federal framework for sovereign public digital infrastructure, names ODF and PDF/UA as the mandated document formats, to the exclusion of proprietary alternatives. The IT Planning Council, the body through which the federal government and the Länder coordinate public administration information technology, has committed to ODF. NATO and the European Commission have mandated it.

The decision is not a European one. Taiwan adopted ODF as a national standard in 2009 and has required it as the government’s document format since January 2015, a policy its Ministry of Digital Affairs describes in terms of software equality, digital sovereignty and sustainable development. Brazil has required federal executive bodies to follow the e-PING interoperability framework, built on open standards, since 2005. Public administrations on almost every continent have taken comparable decisions over the past two decades.

What has changed recently is the reasoning. The case for moving away from proprietary office software was once made primarily as a cost saving. It is now made as the preservation of independence, meaning the ability of a public body to act without asking permission from a foreign supplier. Several of the migrations announced in the past year were presented in exactly those terms, with the cost argument set aside. At least one European defence organisation has stated that its decision was not about money at all.

The alternative to lock-in already exists, is mature, is an international standard, and is a legal requirement in several European jurisdictions.

Further reading

Start here

• What is Digital Sovereignty
• There is no digital sovereignty without ODF
• The characteristics of a truly open document standard format

Format comparison and lock-in

• ODF is the future, OOXML is the past
• Why ODF and not OOXML
• How proprietary formats have become Microsoft’s main tool for lock-in
• Document formats: a mystery to many
• The non-technical dependency layers: the Calendar and the Invoice

Policy and adoption

• Twenty years on, ODF is still the only open standard for office documents, and the only one governments can trust
• Germany’s sovereign digital stack mandates ODF
• Policy and digital sovereignty – TDF Annual Report 2025
• Euro-Office: sovereign in name only, or in reality too?

Technical reference

• What is the Open Document Format (ODF)?
• A technical dive into ODF
• Understanding ODF file types: .odt, .ods, .odp and beyond
• What’s new in ODF 1.3 and 1.4
• ODF v1.4 approved as an OASIS standard