+.I -reference:ALIAS=ASSEMBLY
+Extern alias reference support for C#.
+.Sp
+If you have different assemblies that provide the same types, the
+extern alias support allows you to provide names that your software
+can use to tell those appart. The types from ASSEMBLY will be
+exposed as ALIAS, then on the C# source code, you need to do:
+.Sp
+.nf
+ extern alias ALIAS;
+.fi
+To bring it into your namespace. For example, to cope with two
+graphics libraries that define "Graphics.Point", one in
+"OpenGL.dll" and one in "Postscript.dll", you would invoke the
+compiler like this:
+.Sp
+.nf
+ mcs -r:Postscript=Postscript.dll -r:OpenGL=OpenGL.dll
+.fi
+.Sp
+And in your source code, you would write:
+.Sp
+.nf
+ extern alias Postscript;
+ extern alias OpenGL;
+
+ class X {
+ // This is a Graphics.Point from Postscrip.dll
+ Postscript.Point p = new Postscript.Point ();
+
+ // This is a Graphics.Point from OpenGL.dll
+ OpenGL.Point p = new OpenGL.Point ();
+ }
+.fi
+.TP