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.