WinRT uses Partition II of the ECMA 335 standard1 (Metadata Definitions and Semantics) to describe types. This is the same standard used by the .NET Framework to encode assembly metadata. Therefore, many of the same tools you use to inspect .NET assemblies can be used to explore WinRT types. Visual Studio 2013 ships with the Microsoft Intermediate Language (MSIL) disassembler, also known as
ildasm.exe. In the same way assemblies are encoded in files that end with a DLL extension (for Dynamic Link Library), WinRT encodes type data in files that end with the
winmd extension (Windows Metadata). Types must follow a set of specific standards for WinRT.
WinRT components ...