XlSuite's source code is licensed under an Attribution Share Alike license.

You are free:
  * to Share -- to copy, distribute, display, and perform the work
  * to Remix -- to make derivative works

Under the following conditions:
   * Attribution. You must attribute the work in the manner specified by the
     author or licensor.
   * Share Alike. If you alter, transform, or build upon this work, you may
     distribute the resulting work only under a license identical to this one.

  * For any reuse or distribution, you must make clear to others the license
    terms of this work.
  * Any of these conditions can be waived if you get permission from the
    copyright holder.

See http://creativecommons.org/licenses/by-sa/2.5/ for the full details.