The DAMappedNode class is a pre-made base class for mapping OPC Data Access nodes. The UAMappedNode class is a pre-made base class for mapping OPC-UA data nodes.
You may (but do not have to) use this class as a base class for your objects that you map to OPC Data Access (or OPC-UA data) nodes. The class is already annotated with the DAType (or UAType) attribute, and contains properties that are mapped to useful meta-members, such as the NodeDescriptor property.
Sometimes it is not possible to use these mapped node classes, usually because you already have a class hierarchy where your objects are derived form a different base that you cannot change. In other cases, however, the DAMappedNode (or UAMappedNode) class serves as a handy shortcut that can make your code shorter.