.NET Framework was always called .NET Framework and not renamed from
NET 4 to .NET Framework. There was a time where .NET was applied as a prefix/suffix to everything Microsoft released. Microsoft Windows Server .NET. that had nothing to do with the framework/CLR/programming platform but with Internet connected features.
Fair enough - I meant that, at least in Microsoft's own communication, they started more consistently referring to .NET Framework 4.x to differentiate it from first .NET Core and later .NET.
While it was always called .NET Framework, it was very commonly referred to simply as .NET (e.g. .NET 4.5) - and the "Microsoft .NET" logo was widely used in .NET Framework branding/marketing.
