ECMA-334 C# Language Specification

20.3: Fully qualified interface member names

An interface member is sometimes referred to by its fully qualified name. The fully qualified name of an interface member consists of the name of the interface in which the member is declared, followed by a dot, followed by the name of the member. The fully qualified name of a member references the interface in which the member is declared. [Example: For example, given the declarations 
interface IControl  
{  
   void Paint();  
}  
interface ITextBox: IControl  
{  
   void SetText(string text);  
}
the fully qualified name of Paint is IControl.Paint and the fully qualified name of SetText is ITextBox.SetText. In the example above, it is not possible to refer to Paint as ITextBox.Paint. end example]

When an interface is part of a namespace, the fully qualified name of an interface member includes the namespace name. [Example: For example 
namespace System  
{  
   public interface ICloneable  
   {  
      object Clone();  
   }  
}

Here, the fully qualified name of the Clone method is System.ICloneable.Clone. end example]