I've always found Portable Class Library (PCL) configuration to be a bit of a mystery. In simple cases, it's simple: start a new PCL project in Visual Studio, select the environments you want to support, and away you go. But what's going on under the hood, and what do all the options mean? How do I do this without Visual Studio? Background: supporting Universal Windows Applications in Noda Time Recently, I had a feature request for Noda Time to support Windows Phone 8.1 and Universal Windows Applications[...]