Mono is a platform for running and developing applications based on the ECMA/ISO Standards. Mono is an open source effort led by Xamarin. Mono provides a complete CLR (Common Language Runtime) including compiler and runtime, which can produce and execute CIL (Common Intermediate Language) bytecode (aka assemblies), and a class library.

This package includes a version of the GAC (Global Assembly Cache) tool (gacutil) used by Mono to store shared CIL (Common Intermediate Language) libraries, for CLI 4.0