Differences between assembly references

Question

On some machines after add reference to assembly in csproj generated the next tag.

<Reference Include="Microsoft.Expression.Interactions">
  <HintPath>..\Libs.SL\Blend\Microsoft.Expression.Interactions.dll</HintPath>
</Reference>

But on some machines generated reference with version, culture, token and processor architecture:

 <Reference Include="Microsoft.Expression.Interactions, Version=5.0.5.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">
  <SpecificVersion>False</SpecificVersion>
  <HintPath>..\Libs.SL\Blend\Microsoft.Expression.Interactions.dll</HintPath>
</Reference>

Why is this?

Answer 1

Extracted from msdn:

Processor architecture is added to the assembly identity in the .NET Framework version 2.0, to allow processor-specific versions of assemblies. You can create versions of an assembly whose identity differs only by processor architecture, for example 32-bit and 64-bit processor-specific versions. Processor architecture is not required for strong names. For more information, see AssemblyNameProcessorArchitecture. In this example, the fully qualified name indicates that the myTypes assembly has a strong name with a public key token, has the culture value for US English, and has a version number of 1.0.1234.0. Its processor architecture is "msil", which means that it will be just-in-time (JIT)-compiled to 32-bit code or 64-bit code depending on the operating system and processor.

Code that requests types in an assembly must use a fully qualified assembly name. This is called fully qualified binding. Partial binding, which specifies only an assembly name, is not permitted when referencing assemblies in the .NET Framework.

All assembly references to assemblies that make up the .NET Framework also must contain a fully qualified name of the assembly. For example, to reference the System.Data .NET Framework assembly for version 1.0 would include:

See more in source:

http://msdn.microsoft.com/en-us/library/k8xx4k69.aspx

Answer 2

These lines don't help your application to find the right reference or make a fully qualified assembly name, these lines help Visual Studio to find the reference. Probably you will find these lines only if VS had problems to identify which dll to load.

This is, I know, not the answer that you're expecting :) but I hope it may help you to search in the rigt direction.

Answer 3

I'm not 100% sure, but according to the usual behavior model of .NET Assemblies , in second case you get detailed description (fully qualified name) of the referenced assembly as there are more then one version of the assembly on the machine.

In this way compiler knows which assembly exactly is referenced in your project.