The C# Language Specification is the definitive决定性的；最后的；限定的 source for C# syntax and usage.
This spec contains detailed information about all aspects of the language, including many points that the documentation for Visual C# doesn't cover.
You can download this spec from the Microsoft Download Center.
If you've installed Visual Studio 2013, you can also find the spec on your computer in the Program Files (x86)/Microsoft Visual Studio 12.0/VC#/Specifications/1033 folder.
However, installations of Visual Studio Express 2013 don't include this file.
VS2015安装之后，也可以找到这个
C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC#\Specifications\1033
网上的下载地址，从1.0到5.0都有
http://csharpindepth.com/Articles/Chapter1/Specifications.aspx
See Also
C# Reference
C# Programming Guide