New Post: Datfolder permissions

You did it correct, but in regards to understanding, you need to know that your Content.MyDataType is 100% just as fine an interface as if you had created it in Visual Studio. So while writing code there is no, nada, nicht difference of referencing Content.MyDataType or My.Interface.I.Created.In.VisualStudio.

IPage and Content.MyDataType are both pure CLR types.