The name "aspnet" vnext (ASP.NET 5) is a bit misleading. You can really set up new C # class library projects using vnext and the project.json file.
In the new project.json class library, you choose which framework you want to customize. In beta version 4 and VS 2015 RC, the default target structures are dnxcore50 and dnx451. Dnx451-enabled projects will still have access to the entire .NET platform in the same way as previous C # projects. The dnxcore orientation will give you access to a much smaller size and modulation ability for your project, so you will only include parts of the .NET Framework that you really need.
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