what is the right versioning strategy for different version of .NET

What is the开发者_运维技巧 right way to version assemblies for different versions of .NET?

For example, if I have an assembly foo.dll and I produce a version for .NET 2.0 and a version for .NET 4.0, what is the best option:

• Provide two assemblies foo.20.dll and foo.40.dll
• Allow only one version installed on a given computer
• Provide two assemblies with the same short name (foo.dll) but different versions (2.0.0.0 and 4.0.0.0)
• Same as previous case but with different version (x.0.0.2 and x.0.0.4)
• Use same name and version but different public key token
• Other?

I'll go with the same short name and different versions. That's what the Framework does so people using .NET should already understand this.