Hi Scott,

To understand how Multi-Targeting in Visual Studio 2008 works and affects
the generated assembly:

1) Starts from .NET Framework 2.0, Visual Studio 2005 is actually using
MSBuild to do the compiling. [1]

2) If you compare the project files targeted for .NET 2.0 and 3.5, you will
see a difference about a property named "TargetFrameworkVersion", which
will cause MSBuild to use assemblies in specified framework version. Please
see following blog from MSBuild team:

#MSBuild Team Blog : Multi-Targeting : How does it work?
http://blogs.msdn.com/msbuild/archive/2006/11/15/multi-targeting-how-does-it
-work.aspx

3) Also, please note that .NET Framework 3.0/3.5 actually doesn't
introduced a new CLR version, they are still built on top of the CLR 2.0,
except that installing 3.0/3.5 will update to .NET Framework 2.0 sp1:

#The Moth: .NET Framework 3.5
http://www.danielmoth.com/Blog/2007/06/net-framework-35.html

4) To use command line tool to build your solution/project, just use
msbuild. The 3.5 version is located at
%windir%\Microsoft.NET\Framework\v3.5; the 2.0 version is located at
%windir\Microsoft.NET\Framework\v2.0.50727.

[1] With one exception, C++ projects are still built with VCBuild:

#Srikanth R : Difference between MSBuild and devenv
http://blogs.msdn.com/srikanthr/archive/2007/05/07/difference-between-msbuil
d-and-devenv.aspx

Hope this helps.

Regards,
Walter Wang (wawang@online.microsoft.com, remove 'online.')
Microsoft Online Community Support

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