How much of C# can I use in the ‘Scripting transformation’

Question: How much of C# can I use in the "Scripting transformation"?

Answer: 

You can use all types that are declared in:
System.dll
System.Linq.dll
System.Web.dll
and (both conditions must meet) have the following namespaces:
using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Reflection;
using System.Security.Claims;
using System.Text;
using System.Web;