I see a number of preprocessor symbols listed at http://unity3d.com/support/documentation/Manual/Platform%20Dependent%20Compilation.html, but I don’t see a catch-all UNITY symbol.
I would like to share some C# source code between Unity and a Visual Studio project, but would prefer there to be a UNITY symbol I can #if against for in Unity/MonoDevelop. Am I not seeing a known symbol, or is there a way to add this symbol to both Unity and MonoDevelop?