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Niklas Lindström
Pondering and hacking for comprehension.
Pondering and hacking for comprehension.

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Free data!

tl;dr - If you publish data, attach the CC0 license to it, but that’s basically just advertising - don’t think it means anything.
If you use data, you do not have to care much about the data license.
If you republish data, it’s a bit more complicated, but not as horrible as you might think.

Imagine a student reading a CC-BY-SA published textbook on compilers. Next thing, based on that knowledge, he writes a parser and publishes the binary on the Web. Does he have to acknowledge the textbook? Does he have to publish his code under the same license?

Imagine a designer creating an image with GIMP, a fantastic open source image processing tool, published under the GPL. Or a developer writing his code in Eclipse. Or a website being served from a Linux box. What legal implications does it have for the license of the image? For the source code? For the served page?

Imagine a search engine that changes its background color depending on the type of thing you are searching for. You enter a city - it turns gray. You enter a person - red for females, blue for males, and purple for others. You enter a company - yellow. And so on. Let us assume that the search engine does that by figuring out the thing you are searching for and then asking DBpedia for its type. Since DBpedia is licensed under CC-BY-SA, does this mean we have to put a link on the search result acknowledging DBpedia? Does this mean we have to publish our search index under CC-BY-SA as well?

Imagine Red Cross publishing pages about the countries they work in, and adding the population data to each of them from Freebase, the location from OpenStreetMaps, the local name of the country from GeoNames, and the capital from DBpedia. What amount of legal disclaimer would need to be displayed on the page? Maybe some of the data items derive from another source? What about their licenses? What about this license stacking effect?

There are some rather vague ideas floating about how the whole intellectual property law apparatus works for data. I have mulled over this for a long time, and read more laws and court cases than I care to admit. I want to try to make a few points in the following.

Let’s start with the basics. What laws do actually apply?

Copyright law protects the expression, not the idea - the form, not the content. You can watch the newest Iron Man movie, and you are legally allowed to annoy your friends with retellings of the movie as often as you want. But you are not allowed to film it with your phone camera in the theater and display it to your friends. If you learn something from a textbook, you are free to write your own textbook, adding other knowledge you have acquired, possibly from other textbooks and publications. Only if you start copying the original texts to closely, you will get into legal trouble.

Almost all of the above mentioned licenses - all Creative Commons licenses currently available, as well as the GFDL or the GPL - are based on copyright laws. The GPL has started, as Stallmann admits, as a legal hack of copyright law. This makes a lot of sense, since these licenses have not meant to cover data, but expressions: texts, music, and the like. This means, these licenses cannot extend beyond that. They only cover the expression. They cover the actual RDF/XML file, the string of characters. Not the content. Not the graph.

(Note that ODBL and the current draft of the upcoming fourth revision of CC go beyond copyright and include database right where applicable, i.e. within the legislation of the EU. This extension is irrelevant for the US.)

This means that such licenses, like GFDL for data, have no restricting effect if you want to use the data. Only if you want to republish the data files more or less verbatim (in whole or partially, standalone or as part of a bigger project), you need to think about the original license. Merely including the data (not the files!) has no effect stemming from copyright.

This also makes intuitively sense: if someone takes Wikipedia and counts the distribution of words and letters in Wikipedia, the subsequent publication of the results is not restricted by the original license Wikipedia was published. If someone takes the whole Web, and creates a graph of all links on the Web, and starts to apply some algorithms on this graph, the subsequent usage of the results of these algorithms are not subject to any of the licenses of the original texts published on the Web. Copyright simply does not extend this far. And that is good.

So much to copyright. Unfortunately, the European Union went a step further. They recognized that copyright does not apply to databases. They also recognized that the EU was not doing well in their competition against the US, with regards to publishing databases. So they decided to level the field by introducing a completely new right, the database right. This protects the effort that goes into creating databases - basically their schema (which columns should I have) and the coverage (which rows do I have in my database). Ten years later the EU made an evaluation of the effectiveness of the laws, and came to some interesting conclusions: first, technically the newly database rights made things more complicated; second, most publishers obviously do not understand it, but are happy with what they think it means (which usually contradicts with what it actually means); and third, it completely failed in its goal to advance the database publishing sector. The report offers options to drop the whole database rights thing again, but so far nothing has happened.

Also, this novel database right got a few major blows by the European Court of Justice, where it clearly stated that the right does not cover the creation of the database, merely the effort put into obtaining, selecting, and cleaning a database. This means, e.g. that the publication of match dates and fixtures by FIFA can not be protected under the database right. On the other hand, if an external Website keeps statistics of all FIFA player, how much their cost, where they currently are, etc., then their database as a whole could be protected.

But to make it clear: the database right does not apply to single data items in the database: should I keep a database of all cities in the UK and their populations, and if someone asks for the population of Oxford from my database, the database rights do not prevent them from republishing and using that data item as they like. Eurostat cannot sue you if you tell someone the population of France.

To summarize on database rights: the EU, and only the EU, have introduced in 1996 the so called database rights. They are independent of copyright, and cover a database as a whole in certain circumstances. If you are in the EU, and want to use the data, database right does not restrict you. It only restricts you from republishing the database as a whole or in relevant parts.

Besides the legal foundations of the data licenses, one also has to consider that copyright law refers dominantly to the right to copy the data, not to use it: if you want to count how often certain explicit words are uttered in a movie like Pulp Fiction, you are free to do so. If you want to count and compare the death count in certain books and movies (like, Rambo, War and Peace, and the Bible - the results might surprise you), you are free to do so. You are free to publish the results, and you are even more free to use them internally in your organization.

Having said that, I still recommend to add the CC0 license to a dataset when you publish it. I grudge every time I do it, but it still makes sense. Not because I believe that it means much: as said, the data in it is free anyway. But because a lot of other people believe that it means a lot. They might believe that if they integrate a point of data from a CC-BY-SA licensed dataset in their own dataset, they have to publish it under CC-BY-SA as well. They might believe that mixing a CC-BY-SA dataset with an ODBL dataset and displaying the results is legally impossible. Maybe they don’t even believe it, but they are required to ask their lawyers, and their lawyers will prefer to play it safe for their clients (it is their job!) and advise them accordingly. And for all of these people, the CC0 license is an item of assurance. So if you want your dataset to be usable by them, just add a CC0 license to it. And grudge about it.

There is a completely independent aspect of why it could make sense to cite your data sources, which is trust and provenance. Even if a dataset is not published under a CC-BY-like license, meaning that it requires attribution, it often makes sense to keep the provenance and attribution intact - simply because the user of your data might ask for the source themselves, and might want to check on their credibility. But attribution for increasing your credibility is something entirely different than attribution because you think you are legally obliged due to the used data.

If I were an organization or individual with sufficient financial backup, I would even offer to pick up your legal battles if a data publisher ever sues you for using their data (not for republishing it verbatim, though). I hope that maybe an organization or individual will step up at some point to do so, but I wouldn’t hold my breath for it. Both the US Supreme Court and the European Court of Justice have repeatedly decided in favour of the freedom of data, be it the results of games, be it telephone numbers, be it horse racing fixtures. 

So, as paradoxical as it sounds: Data is free. Free the data!

There is a battle over minds going on. The one side fights for the establishment and extension of intellectual property rights. In the last decades, even years, they have achieved some considerable victories. Copyright law, as it was introduced in the United States, was meant for 14 years, and had to be explicitly stated. Today it holds not only for the lifetime of the creator, but also an additional 70 years (to incentivize the creator to produce more, because an author would be much less motivated to write if they knew that half a century after their death their highly beloved publisher wouldn’t make profit out of their work anymore). Today, copyright applies automatically, without any registration or statement. There is no need to put the little c in a circle anywhere. It is there, automatically, everywhere.

The extension from works to content, from expression to ideas, is another dimension, this time in scope instead of time, in the continuous struggle to extend and expand intellectual property rights. It is not just a battle over the laws, but also, and more importantly, over our believes and minds, to make us more accepting towards the notion that ideas and knowledge belong to companies and individuals, and are not part of our commons.

Every time data is published under a restrictive license, “they” have managed to conquer another strategic piece of territory. Restrictive in this case includes CC-BY, CC-BY-SA, CC-BY-NC, GFDL, ODBL, and (god forbid!) CC-BY-SA-NC-ND, and many other such licenses.

Every time you wonder what license some data has that you want to use, or whether you need to ask the data publisher if you can use it, “they” have won another battle.

Every time you integrate two data sources and want to publish the results, and start to wonder how to fulfill your legal obligation towards the original dataset publishers, “they” laugh and welcome you as a member of their fifth column.

Let them win, and some day you will be sued for mentioning a number.

I am not linking to the obvious texts, which are the actual laws. Read them. They are not as impenetrable as you think. I mean, heck, if you can make sense of an RDF/XML file, you shouldn’t be scared of some legal text.

Evaluation of the European Commission on the effect of database rights 

US Supreme Court, Baker v. Selden - on the extent of copyright with regards to the expression, not the content

This text was written by me on a Saturday morning, as a completely personal opinion. It does not represent the official point of view of any current, former, or future employer, nor of any project I ever was, am, or will be affiliated with or am thought to be affiliated with.

Available on a permanent personal URL here: 

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Truly saddening and terrible. :( I never knew him, but Aaron's brilliant mind has inspired me in many ways, technically and personally.

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Structured Data Website Launch

A number of Web developers from the RDFa, Microdata and Microformats communities announce the launch of the Structured Data website and community. There are a number of syntaxes for expressing structured data in HTML today: RDFa, Microdata and Microformats. While each syntax has its own parsing rules and data model, the underlying concept among all of them is the same - to express Structured Data in HTML.

The Structured Data website ( provides resources to learn about, markup and debug structured data in HTML, including RDFa, Microdata and Microformats. One of the new features, not available anywhere else, is a unified Structured Data Linting Service (, complete with Google Rich Snippets and examples ( in both Microdata and RDFa format. The Structured Data Linter provides a unified service for verifying and visualizing the structured data contained in web pages, and supports the RDFa and Microdata syntaxes, with Microformats support on the way.

At the time of this announcement, the Google and Microsoft testing tools do not support markup in RDFa or Microdata. The need for such linting service has been expressed many times on the mailing list and we are happy to announce that the service is now available. Gregg Kellogg has been instrumental in creating the linting service with support from Stéphane Corlosquet. Web developers may now use the linter service to ensure that their Microdata or RDFa markup is valid.

The Structured Data Linting Service is a beta launch and thus contains a number of bugs. That said, we felt that it would be best to get this tool into the hands of the Web developer community. We invite the Web developer community to try it out, report bugs (, suggest new features ( and contribute new ideas and code. All of the source code is released under a public domain dedication and is available on github (
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