EasyOPC Extensions for .NET is a pack of .NET classes that adds more functionality to the EasyOPC.NET and EasyOPC-UAcomponents. It is built upon and relies on EasyOPC.NET and EasyOPC-UA, so in fact you could build all these extensions yourself, but it is meant to provide a ready-made, verified code for useful “shortcut” methods to achieve common tasks.
Technically, Specialized Client Objects are also similar to layered extensions.
The Python support in QuickOPC is built on top of .NET API. Consequently, the layered extension for .NET are also available in Python.