Good software needs good documentation. But how do we define “good” in this sense? And what does the future hold? Find out in episode 4 of the LibreOffice Podcast! (This episode is also available on PeerTube.)

When different systems, applications or organisations need to communicate with each other and actually understand what is being said, interoperability is key. It enables a hospital’s software to communicate with an insurance company, for example, or one vendor’s inventory system to synchronise with another’s logistics platform.

At the heart of many of these data exchanges is XML.

XML (Extensible Markup Language) may not be new or flashy, but it remains one of the most powerful tools for achieving reliable, structured interoperability across diverse platforms.

Why is interoperability so hard?

Systems are built using different programming languages, data models and communication protocols. Without a shared format or structure, exchanging data can result in a complex web of custom APIs, ad hoc conversions, and manual adjustments.

To get systems working together seamlessly, you need:

• A standardised structure for data.
• A way to validate that structure.
• A format that is language-agnostic and platform-neutral.

XML ticks all these boxes.

How XML enables interoperability

1. Self-describing structure

XML uses tags to clearly label data:

<customer>
   <name>Maria Ortega</name>
   <id>87234</id>
</customer>

This means that a receiving system doesn’t have to guess what each field means, as it is explicitly defined. This reduces the risk of misinterpretation and supports automated parsing.

2. Schema validation

Using XSD (XML Schema Definition) or DTD (Document Type Definition), you can define the rules that an XML document must adhere to, such as which elements are required, which data types are valid and what the structure must be.

This is critical for:

• verifying incoming data
• preventing malformed or incomplete exchanges
• ensuring consistency across multiple systems

3. Namespaces for avoiding collisions

XML namespaces prevent tag name conflicts when data from different sources is combined.

<doc xmlns:h=”http://www.w3.org/TR/html4/” xmlns:f=”http://www.w3schools.com/furniture”>
   <h:table>…</h:table>
   <f:table>…</f:table>
</doc>

Without namespaces, systems could misinterpret elements with the same name but different meanings.

4. Cross-platform compatibility

XML is plain text. Any system that can read a file can read it, whether it’s written in Java, .NET, Python or COBOL. This makes it ideal for long-term data exchange and integration between legacy and modern systems.

XML in real-world interoperability

Healthcare: HL7 CDA/FHIR

Hospitals, clinics, insurance providers and pharmacies rely on XML-based formats to exchange clinical records, billing data and prescriptions. HL7’s CDA (Clinical Document Architecture) is a strict XML schema that is used worldwide.

In government, XML is used for e-government forms and tax data.

Tax filings, business registrations and compliance documents are often submitted in XML format. This ensures consistent structure across various jurisdictions and software vendors.

Publishing: DITA and JATS

XML standards are used for modular content creation and journal publishing to allow interoperability between authors, editors, publishers, and archive systems, even if they are using different tools.

Finance: XBRL

XBRL (eXtensible Business Reporting Language) uses XML to standardise financial reports, enabling regulators, investors and analysts to automatically process and compare data from …

Following the example of the German state of Schleswig-Holstein, which is moving 30,000 PCs from Microsoft Office/365 to LibreOffice, the Danish Ministry of Digitalisation is doing the same.

Caroline Stage Olsen, the country’s Digitalisation Minister, plans to move half of the employees to LibreOffice over the summer, and if all goes as expected, the entire Ministry will be free from Microsoft Office/365 later in the year.

In a LinkedIn post, Olsen summarised the reasons for switching to LibreOffice:

We must never make ourselves so dependent on so few that we can no longer act freely. Because far too much public digital infrastructure is today tied up with very few foreign suppliers. This makes us vulnerable. Also financially.

That is why we are now testing in parallel at the Ministry of Digitization how it works in practice when we work with open source solutions. Several municipalities are doing the same.

Not because we think it’s easy – but because we know it’s necessary to lead the way if we want to create more competition and innovation – and reduce our dependence on the few.

We in the LibreOffice project welcome this move, and look forward to seeing more governments and organisations getting control of their digital sovereignty and using public money for public code.

In my last article, I mentioned XML several times, perhaps assuming that all users had a basic understanding of it. Rereading it, I realised that an introduction to XML was needed for non-technical users, those who use XML every day without realising it, when they open a document, check the weather, place or receive an order online, or issue a digital invoice. XML works silently behind the scenes.

But what exactly is XML and why should it matter to non-techies? I will try to explain it in simple terms.

XML stands for eXtensible Markup Language, a way of organising information in a format that is easy for both people and computers to understand, helping different applications communicate and exchange data using a common language. Put simply, XML is a digital container that clearly labels information.

For example, this is a shopping list in XML format:


<groceryList>
  <item>
    <name>Bread</name>
    <quantity>1 loaf</quantity>
  </item>
  <item>
    <name>Milk</name>
    <quantity>2 litres</quantity>
  </item>
</groceryList>


Labelling helps computers and software understand exactly what each piece of information means.

In a hyperconnected world like ours, where apps and systems share data, XML allows that data to move between very different systems, such as credit card management apps and online shops. Without a common language like XML, communication between these systems would be much more complicated and slower, or even impossible.

So, XML is integrated into most everyday activities, even though it is completely hidden from users:

• All documents created by all office suites use XML, in some cases to facilitate transparency and interoperability, and in other cases to create a hidden layer of complexity with the aim of preventing transparency and interoperability.
• All apps that provide weather forecasts obtain updates by reading XML data issued by weather agencies.
• Almost all e-commerce applications use XML to manage communication between the website, the payment system, the bank and the shipping service.
• All blogs and news sites use XML to automatically transmit new content to readers.

XML is clear and easy to read because it organises data in an orderly manner with labels that are understandable to both humans and computers; it is flexible, as it is not limited to a single type of information and can be customised for different scenarios, from cooking recipes to flight schedules; and it is compatible with all platforms.

To appreciate the value of XML, you don’t need to have a deep understanding of the language, just know that it exists and that – when used properly, as in the case of the ODF format – it has the potential to help users achieve and protect their digital sovereignty.

Of course, it is equally important to know that XML can be used in exactly the opposite way, as is the case with Microsoft 365’s OOXML format (and previously Office), to limit users’ digital sovereignty and perpetuate lock-in through artificial file complexity.

In summary, XML is a silent enabler that ensures that users’ apps, services and data all speak …

Here’s our summary of updates, events and activities in the LibreOffice project in the last four weeks – click the links to learn more…

• We started the month with Episode 3 of the LibreOffice Podcast – this time looking at Quality Assurance (QA) in Free and Open Source Software. Watch it below – or on PeerTube.

• Then we announced the winners in the Month of LibreOffice, May 2025, providing information on how to get sticker packs. We’ve been sending out stickers and merchandise in the last few weeks, with a bit more to come!

• On June 6, we announced LibreOffice 25.2.4, the fourth minor update to our latest stable branch. All users are recommended to upgrade.

• Next, we posted another section from The Document Foundation’s Annual Report, “LibreOffice for End User Privacy”.

• The end of Windows 10 is approaching, so it’s time to consider Linux and LibreOffice! That’s the message behind the “End of 10” campaign, which we’re supporting.

• In the middle of the month, we posted news about a new tutorial added to the wiki, showing how to create colour wheels with LibreOffice.

• Throughout June, we posted various articles about ODF, the Open Document Format used by LibreOffice (and supported in many other office suites): An Analysis of the adoption of the Open Document Format; Understanding ODF compliance and interoperability; and A technical dive into ODF.

• Then we reported back from an event: LibreOffice at the Linux Arena in Pordenone, Italy.

• Before LibreOffice there was OpenOffice, and before OpenOffice there was StarOffice. And how was StarOffice developed? We talked to Stefan Soyka, who worked on the suite in the early ’90s, and has some entertaining stories to tell

• New LibreOffice merchandise is here! We updated our Spreadshirt shop with new designs and many extra items. Buy something and support LibreOffice – some of the proceeds go back to the project!

• Registration is now open for the LibreOffice Conference 2025. Join us from 4 – 6 September in Budapest – we’ll have technical talks, workshops, social events and more…

• And finally, we announced the new LibreOffice 25.2 user guides – awesome work from the documentation team.

Keep in touch – follow us on Mastodon, X (formerly Twitter), Bluesky, Reddit and Facebook. Like what we do? Support our community with a donation – or join our community and help to make LibreOffice even better!

The LibreOffice community has great news: the Writer, Calc, Impress, Draw, and Math User Guides are now available for version 25.2!

Yes, you read that right! With every new LibreOffice release, our Documentation Team works hard to keep up — and this time, we’ve shortened the gap between the software launch and the guides’ publication even more.

These user guides are the ultimate reference for anyone using LibreOffice — whether at home, at work, or at school. From spreadsheets to presentations, from text documents to complex equations: it’s all covered, clearly and accessibly.

The work is 100% community-driven! Jean Weber led the Writer guide, Peter Schofield coordinated the Impress, Draw, and Math guides, and Olivier Hallot headed the Calc guide.

Big thanks also to Dione Maddern, Celia Palacios, Ed Olson, B. Antonio F., Mike Kaganski, and Vasudev Narayanan for their valuable contributions.

Each new edition is more than just an update — it’s a chance to improve clarity, add the latest features, and deliver the best experience possible for end users. These guides complement the built-in LibreOffice Help and are perfect for deepening your knowledge.

The guides are available now for free download in PDF, ODT (OpenDocument format), and HTML (for online reading). And soon, you’ll be able to order printed copies via LuLu Inc.

Get your guides now:

• documentation.libreoffice.org
• books.libreoffice.org

Artwork: Eliane Domingos

Registration is now open for the LibreOffice Conference 2025! Join us from 4 – 6 September in Budapest We’ll have technical talks, workshops, social events and more…

Click here to learn more, and register

To write this article, I went beyond the limits of my technical knowledge, which is that of an advanced user who has studied standard formats and their characteristics in depth, to understand why standard formats – one of the pillars of digital sovereignty – and proprietary formats – their opposite, and one of the biggest obstacles to digital sovereignty – are not perceived as a problem by most PC users, who continue to use Microsoft’s proprietary formats and place the access and availability of their content in the hands of the US company.

To try to remedy this problem, I will try to explain as simply as possible, using non-technical language (which may shock developers, but this article is not aimed at them), some technical features of the Open Document Format (ODF), which make it the cornerstone of an open and vendor-independent ecosystem for office documents, defending the digital freedoms of all users and the governance of their content.

I will begin by explaining how to unpack an ODF file, which is nothing more than a set of XML files and other files (for images and videos) contained within a ZIP folder, in order to examine its internal components and, in particular, the content.xml file, which is the one that contains the body of the document (i.e., the user’s intellectual property).

The aim is not so much to assess conformity (compliance with specifications) and interoperability (the ability to exchange files consistently between tools), as these aspects will always be dealt with by specialists, but rather to understand the advantages for the user of the open and standard format over the closed and proprietary format (which is falsely standard, since it was approved by ISO/IEC in defiance of “their” definitions of standards).

For this reason, I will make a brief concluding digression on the characteristics of the OOXML (Office Open XML) format used by Microsoft Office and Microsoft 365, again to clarify to users the risks they face and the harm they do to themselves and other users when they use DOCX, XLSX and PPTX formats, as well as the ‘gift’ they are giving to Microsoft, to whom they are effectively entrusting the management and future of their content.

Analysing an ODF file

Take any document you have created with LibreOffice. For convenience, I recommend starting with a text document created with LibreOffice Writer, with the ODT extension. Before doing anything else, duplicate the file, because an error in the procedure could make it unreadable, and move the original to another folder.

Rename the copy, replacing the ODT extension with the ZIP extension, without deleting the dot. The file icon will become that of a compressed file. If it becomes white or empty, you have done something wrong or deleted the dot. Check all the steps until the icon becomes that of a compressed file.

At this point, right-click on the icon and select “unzip” or “expand” to extract the contents of the compressed file into a folder with the …