Publication: Open data and free use

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This is a translation of the "Publicatie:Open data en vrij hergebruik" page. Cultural heritage organisations are expected to make photos and metadata from their collections available as open data. But it’s often unclear what this means exactly: does everything need to be available for free? Or is it okay to simply post photos on the internet? And why should carefully gathered information just be given away free of charge? This article explains what we mean by open data, why it’s a topical issue, and when data really is ‘open’.

Titel Open data and free use (Voorkeurstitel)
Locatie [ ]
Jaar van uitgave 2020
Rechten CC-BY-SA
Persistent ID


introductie | bibliotheekcollecties | archiefcollecties | museumcollecties | audiovisuele collecties | archeologische collecties | immaterieel erfgoed | onroerend erfgoed | documentaire collecties | "toegankelijkheid" is not in the list (waarderen en selecteren, digitaliseren, digitaal geboren materiaal, digitaal archiveren, toegang en hergebruik, linked (open) data, rechten en privacy, digitale strategie, metadata) of allowed values for the "Cest:aboutExpertise" property.toegankelijkheid | "rechtenbeheer" is not in the list (waarderen en selecteren, digitaliseren, digitaal geboren materiaal, digitaal archiveren, toegang en hergebruik, linked (open) data, rechten en privacy, digitale strategie, metadata) of allowed values for the "Cest:aboutExpertise" property.rechtenbeheer | geluid | bewegende beelden | rasterbeelden | vectorbeelden | tekst | 3D-beelden |


Bert Lemmens (meemoo, Flemish Institute for Archives)


The word ‘open’ has multiple interpretations, which can cause confusion. We see it crop up in terms such as ‘open source’ (software with a source code that anyone can modify and edit), ‘open content’ (free access to original work), ‘open science’ (free access to scientific research) and ‘open knowledge’ (free access to knowledge in general). ‘Open data’ could be interpreted as ‘free data’, but as Richard Stallman explains: ‘Think free as in free speech, not free beer.’ In this context, ‘free’ refers to four fundamental freedoms:

Robin Rice / CC BY
  • you can use data freely, i.e. without restriction from personal or societal sensitivities or preferences, for example;
  • you can study data freely, i.e. you are free to use the knowledge acquired in the process;
  • you can distribute data freely, i.e. you can make copies to share with anyone you want;
  • and you can modify data freely, i.e. you can process, improve, expand or reduce data for your own purposes.

These four freedoms apply for everyone, regardless of what purpose the data is used for.


This doesn’t mean that the use of open data cannot be restricted. And even though some restrictions make certain forms of re-use more difficult (or even impossible), they can still be useful for safeguarding or even enhancing the openness of data, such as attributing the data source or author, or obliging modified or derived versions to also be made available as open data (= share-alike). Personal data protection regulations can however require that open data is anonymised.

Engine for social change

The open data movement has developed in parallel with the ongoing digitisation of society. And the ability to collect large amounts of data has led to the expectation that data could also become an engine for social change. But in order to maximise the chance of data leading to new insights, it needs to be shared as widely as possible. This ambition is dented, however, when technology companies start commercialising access to data by invoking copyright laws and hiding data behind licences, patents and paywalls.

But the open data movement has still managed to succeed in putting open data on the societal agenda over recent decades. Indeed, the European Union Open Data Directive has even enshrined in European legislation the idea that public sector information should be made available for re-use as much and as easily as possible. And since museums, libraries and archives in Flanders are largely publicly funded, they are also expected to make photos and metadata freely available for re-use.

How to go about it?

Open data must satisfy four criteria:

  1. The data is made freely available in its entirety. You may charge a marginal cost for reproduction, provision and distribution, however. The data should preferably be available for download via the internet, with any usage restrictions clearly indicated;
  2. The data can be read by machines;
  3. The format is open and supported by at least one open-source tool;
  4. And last but not least, the data is accompanied by a ‘CC0 public domain dedication’ or published under an open licence[1], so users can unequivocally establish that the data is freely available.


Creative Commons Licences: and Flemish Government Model Licences: (Dutch only)