The Mono code under the mcs/ directory is licensed under various different licenses: GNU GPL: details avaliable in the file LICENSE.GPL GNU LGPL: details available in the file LICENSE.LGPL MIT X11: text available in the file MIT.X11 MPL: text available in the file LICENSE.MPL For your convenience copies of the GNU GPL and GNU LGPL are located in the file COPYING and COPYING.LIB. * Class Libraries: All of the core classes licensed under the terms of the MIT X11 license. Third party libraries that we distribute for convenience reasons are distributed under their own terms (all of them allow development of proprietary applications with them). Third party libraries include: ByteFX.Data, ICSharpCode.SharpZipLib, Npgsql, MicrosoftAjaxLibrary. The Microsoft.JScript assembly is covered by the MIT X11 and the Mozilla MPL license as it contains ported pieces of code from Rhino, the Mozilla JavaScript implementations * Mono C# compiler: Dual licensed MIT X11 and GNU GPL. * Mono Basic compiler: GNU GPL. * Various tools in the `tools' directory: GNU GPL.