It is [sometimes suggested](http://lists.okfn.org/pipermail/odc-discuss/2009-November/000211.html) that there isn’t a real difference in terms of “openness” between share-alike (SA) and non-commercial (NC) clauses — both being some restriction on what the user of that material can do, and, as such, a step away from openness.
**This is not true.** A meaningful distinction can be drawn between share-alike and non-commercial clauses (or any other clause that discriminates against a particular type of person or field of endeavour), with the former being [“open”](http://opendefinition.org/okd/) and the latter being not [“open”](http://opendefinition.org/okd/).
This distinction is important. It has relevance, for example, as to why [Open Data Commons](http://www.opendatacommons.org/) should not provide NC licenses but will provide [a share-alike one](http://www.opendatacommons.org/licenses/odbl/). As well as to Creative Commons whose set of licenses includes both share-alike and non-commercial options. As such, not all CC licenses are open and CC licenses are are not all mutually compatible. This is something of an irony as it means that Creative Commons provide a set of licenses that don’t, in fact, result in a commons.
## What’s the Problem? Why Does This Matter?
> What’s the problem with NC licenses, aren’t “SA” licenses a step away from open too? And if we debate this, don’t we just end up having a pointless license holy war?
The distinction between NC and SA licenses isn’t about “holy war” but something very practical: license compatibility and the integrity of the “open” commons. The core of a “commons” of data (or code) is that one piece of “open” material contained therein can be freely intermixed with other “open” material.
This interoperability is absolutely key to realizing the main practical benefits of “openness” which is the ease of use and reuse — which, in turn, mean more and better stuff getting created and used.
The [Open Knowledge/Data Definition](http://opendefinition.org) functions as a “standard” to ensure interoperability just in the same way as normal tech standards operate (but in this case for licenses rather than for a piece of hardware or software). The aim is to ensure that any license which complies with the definition will be interoperable with any other such license meaning that data or content under the one license can be combined with data or content under the other license.
Share-alike or attribution requirements are allowed within the definition precisely because they do not break this interoperability (and may even help promote the commons by ensuring material is “shared back”). Non-commercial provisions are not permitted because they fundamentally break the commons, not only through being incompatible with other licenses but because they overtly discriminate against particular types of users. (I should emphasize here that the definition is directly following the line set out in the original open source definition …)
Thus, there is a meaningful distinction between attribution and share-alike requirements and other such as non-commercial (NC), and it is a distinction that merits the description of share-alike licenses as being open but non-commercial licenses as not being open.
## Isn’t It Just About Degree?
> Yes, NC and especially ND are more restrictive, but stating that NC
> licenses aren’t open is wrong – they’re just not as open.
This is incorrect.
To reiterate: it is a mistake to view the set of licenses as some continuous spectrum of ‘openness’ with PD at one end and full rights reserved at the other — with the implication that all licenses in between are more or less open.
There are significant discontinuities and in particular we can meaningfully partition the set of licenses into open and not-open based on a) their interoperability b) the freedom they provide to *all* persons (and companies) to use, reuse and redistribute.
## But You Can’t Trademark Openness …
> it’s annoying that someone claims to be releasing data openly, but it turns out to be
> NC and no-compete and a bunch of other stuff. It would be nice to say to them – “you can’t claim to be open because you don’t meet this
> definition”. But unfortunately it would probably be difficult to get
> the trademark on the word “open”
It’s quite right that you can’t trademark openness — and no-one should want to! However, we can make an effort as a community to have a clear shared meaning for “open” in relation to data and content along the lines of — just as the open source definition has done for code. By insisting on this meaning we are doing something valuable: creating a standard and maintaining interoperability.