Porting to .NET standard version, you may be source identical to a portable library, but the platforms supported may not.
For example .NET standard 1.6 might be the lowest version that has your api's available from portable Profile47. Profile47 supports .net 4.5 or later, nut .NET Standard 1.6 only supports 4.6.1 and later!
With the new multi-targeting with the new msbuild 15 csproj/fsproj (also VS2017) is it possible to compile for both a Portable Library and .Net Standard at the same time to make the transition easier?