Open Source Licenses

Perhaps the most critical component of OSS is the license that protects the rights of both the software author and user. The Open Source Definition[4] lists nine important criterion that OSS licenses must support. For our discussion the most important are:

Free Redistribution:

the software cannot require royalties or fees

Source Code:

the source code must be available on request

Derived Works:

modification and redistribution of the software must be allowed

No Discrimination Against Fields of Endeavor:

no restriction may be made on how or by whom the software is used

Therefore, a license does not conform to the OS definition if it restricts the rights of some users (e.g. free to academic users, but not to commercial users). The intent behind these not-quite OS licenses is this: you can use or examine the code for non-profit purposes, but if you are going to use this code to make a profit, you have to share some of it with the authors. Although it enables an algorithm's implementation to be validated it violates some of the primary criteria of OSS: redistribution, derived works, and no discrimination.