Well they said .NET Framework, and I also wouldn’t be surprised if they more or less wrapped that up - .NET Framework specifically means the old implementation of the CLR, and it’s been pretty much superseded by an implementation just called .NET, formerly known as .NET Core (definitely not confusing at all, thanks Microsoft). .NET Framework was only written for Windows, hence the need for Mono/Xamarin on other platforms. In contrast, .NET is cross-platform by default.