/langversion (Conformant Syntax) (C# Compiler Options)
Causes the compiler to only accept syntax that is included in the ISO/IEC 23270:2003 C# language specification.
Version 1.0 of the C# specification represents the functionality available with /langversion:ISO-1. http://msdn.microsoft.com/vcsharp/programming/language/default.aspx contains all specifications as Microsoft Word files.
Metadata referenced by your C# application is not subject to /langversion compiler option.
Each version of the C# compiler contains extensions to the language specification, so /langversion does not give you the equivalent functionality of a previous version of the compiler.
Regardless of which /langversion setting you use, you will use the current version of the common language runtime to create your .exe or .dll.
One exception is friend assemblies and, which work under /langversion:ISO-1.
To set this compiler option in the Visual Studio development environment
Open the project's Properties page. For details, see.
Click the Build property page.
Click the Advanced button.
Modify the Language Version property.
For information on how to set this compiler option programmatically, see.