Accessible #1: (Meta)data are retrievable by their identifier using a standardised communication protocol
Once someone has found either your metadata or the data themselves, they - or their machine - should be able to access the (meta)data using standardised mechanisms. This principle states that access should be provided through a standardised protocol. Most often, these are protocols we know from the internet – e.g. http(s) or FTP. This is usually the case, when data are deposited in a trusted repository. However, there might be cases where you will need additional mechanisms such as contract information or similar before someone can access your data. This is perfectly in line with the FAIR principles, if you clearly account for this in the metadata. This may be in the form of contact options that are broadly accepted and easy to use. Examples of this are telephone numbers and email addresses.
Accessible #1.1: The protocol is open, free and universally implementable
A protocol is the technical term for the standard of how data are transported via a network, e.g. the internet. TCP/IP is an example of an open, free and universally implementable protocol that is used as protocol for most of the internet. This means that anyone can use it without having to pay usage fees.
If you choose a protocol with restrictions on usage, you might prevent other people from accessing to your (meta)data, thus making it hard – or even impossible – to use the data you have published. If you use a trusted repository for data publication, the repository will make sure that you are in line with this principle.
Accessible #1.2: The protocol allows for authentication and authorisation when required
One of the most widely believed myths on FAIR data is that FAIR data must be available as open data, meaning that they should be free for everyone to download. This is not the case.
This principle states that if you place data behind some sort of digital wall, being a paywall or a simple approval system for access, the system must allow for some type of authentication and authorisation. This holds for both humans and machines.
Authentication is all about telling a system who you - or your system - are. Authorisation, on the other hand, is the process where the system is evaluating, if you are allowed to access a given resource.
There are many good reasons to place data behind authentication and authorisation mechanisms. But remember, if you have manual processes involved in evaluating who should have access to the data, the repository or storage system must be able to contact you and seek approval. Other systems will let users or systems register themselves and then provide access to the data, while maintaining a logbook of who has been granted access.
Accessible #2: Metadata should be accessible even when the data are no longer available
There are plenty of good reasons why data disappear from repositories and similar places. They may be withdrawn due to the cost of having them online, if no one is left to maintain access to the data, or for other reasons. However, if the metadata about the data set disappear as well, it will leave humans and machines in an “unfulfilled” state, when they try to retrieve the data, e.g. when resolving a persistent identifier, or following a link to the entry of a repository. Therefore, make sure to leave metadata telling that “yes, the data were here, but they are no longer available”. Leaving metadata may also offer information on the context, the authors and the institution, where the data were created, for those looking for further details.
Go to the webpage for A FAIRy tale for more information about the FAIR principles.
Based on 'A FAIRy tale' CC-BY-SA 4.0 ‘DK Fair på tværs’.