I have seen various frameworks targeted in project.json files, using names such as
Full list see http://docs.nuget.org/create/targetframeworks.
The most common TFMs ASP.NET app developers need to know are:
netcoreapp1.0= An application that targets .NET Core 1.0
netstandard1.x= A library that targets .NET Standard 1.x. (e.g.
netstandard1.5). .NET Standard libraries can work on desktop .NET, Windows Phone, Mono, and others.
net4xy= A library or console app that targets desktop .NET Framework 4.x.y (e.g.
UPDATE 3 There is official documentation now. See http://docs.nuget.org/create/targetframeworks.
UPDATE 2 (Dec 9, 2015)
Somewhat official docs are now available from dotnet. See .NET Platform Standard > Nuget
For libraries targeting multiple platforms that adhere to the .NET Standard, these TFMs (target framework monikers) are available.
For platform-specific monikers, these TFMs are available.
UPDATE (Aug 12, 2015)
This Nuget blog post shows additional TFM's available for nuget. It also explains the
Although this is not official documentation, this blog post by Oren Novotny has an excellent table showing the different target framework monikers (image below).