We believe that all of the code in this release (4.6.0) of XFree86 meet the requirements of the Open Source Definition, as maintained by the Open Source Initiative (OSI).
We believe that most of the code in this release (4.6.0) of XFree86 meets the requirements of the Free Software definition as defined by the Free Software Foundation (FSF).
Exceptions to this include the GLX extension and CID font code that are covered by the SGI Free Software License B, version 1.1.