I couldn't figure out the best area label to add to this PR. If you have write-permissions please help me learn by adding exactly one area label.

I think there are a few more cases that could be probably annotated. For example one for consideration is SocketsHttpHandler.IsSupported and there was something in crypto too

@buyaa-n One question just for my information:

How could I use these guards to annotate the APIs which partly throw PNSE based on some condition, e.g. https://github.com/dotnet/runtime/blob/main/src/libraries/System.Net.Sockets/src/System/Net/Sockets/SocketPal.Unix.cs#L32-L38 ? The methods using this one throw on ios/tvos (and a couple of related System.Net.NetworkInformation.Functional.Tests tests fail).

I think there are a few more cases that could be probably annotated. For example one for consideration is SocketsHttpHandler.IsSupported and there was something in crypto too

Thanks, i remember SocketsHttpHandler.IsSupported i will add that, but i don't think ever heard about crypto one

How could I use these guards to annotate the APIs which partly throw PNSE based on some condition, e.g. https://github.com/dotnet/runtime/blob/main/src/libraries/System.Net.Sockets/src/System/Net/Sockets/SocketPal.Unix.cs#L32-L38 ? The methods using this one throw on ios/tvos (and a couple of related System.Net.NetworkInformation.Functional.Tests tests fail).

Not sure, from the code in the link it doesn't look like it does platform check, seems doing capabilities check

The methods using this one throw on ios/tvos (and a couple of related System.Net.NetworkInformation.Functional.Tests tests fail)

That sound like its need UnsupportedOSPlatform on ios/tvos attributes (not guard attributes)