[terrajobst]

Not quite. See this comment for the relationships of the specs: https://news.ycombinator.com/item?id=14971769

.NET Framework, .NET Core, Mono, Xamarin, and Unity are all implementing all the .NET specs. They are share many aspects, but each also bring specific capabilities that the others don't have, so its not very useful to think of these having a superset/subset relationship.

[smitherfield]

Hence the intersection symbols.

[MarkSweep]

I don't think .NET Framework is a supper set of all other implementions of .NET. For example, Mono's SIMD types are not in .NET Framework. It is even possible for types to exist in .NET Core that don't exist in .NET Framework.

I think you could say the following:

    .NET ECMA Spec ⊆ .NET Standard
    .NET Standard ⊆ .NET Core
    .NET Standard ⊆ Mono
    .NET Standard ⊆ Xamarin
    .NET Standard ⊆ .NET Framework

[smitherfield]

You're confusing intersection and union.

[MarkSweep]

Oh, derp, you're right.

[terrajobst]

Still, .NET Framework isn't the superset of everything. As I said, I find your description not useful because it simply doesn't capture how the .NET stacks are designed.