“Each developer holds copyright in his or her code the moment it is written, and because all the world’s major copyright systems—including the US after 1976—do not require notices, publishing code without a copyright notice doesn’t change this.”1
In the recent code sharing session at the AAS 223 meeting, both Alberto Accomazzi and David Hogg mentioned the difficulty of dealing with code that did not carry any license, copyright notice, nor sometimes even author information with it. Such code is difficult to share for transparency, reuse, or expansion. Letting people know whether and how they can use your code and/or share it is a kindness not just to them, but to the community and even yourself, whether you want to retain copyright on the code, choose one of the copyleft licenses, or make your code public domain.
Just beginning to think about licensing and trying to wrap your head around it? TechSoup offers a good introduction on licensing in Making Sense of Software Licensing, and I’ve previously mentioned A Quick Guide to Software Licensing for the Scientist-Programmer from PLoS in our list of general articles that may be of interest to astronomical software users.
If you already know you want an open source license for your open source software (OSS) but don’t know which to choose, the Choose a license site describes different popular open source licenses; it is a good resource for getting an overview of each of them. The Open Source Initiative also offers information on licenses and has a FAQ that is useful for clarifying such terms as copyleft, public domain, open source, and free software in addition to others one runs across when considering licensing.
Interested in retaining copyright within a collaborative free software project? This white paper from the Software Freedom Law Center identifies best practices for doing so. And if you’re thinking about changing a code’s license, you may want to read Bruce Berriman’s informative post, with plenty of resources in it, on his Astronomy Computing Today blog.
What resources have you found helpful for licensing? I am very interested in knowing, and hope you will please share them; thank you!
1 http://softwarefreedom.org/resources/2012/ManagingCopyrightInformation.html