Is Document User Data only accessible from one plug-in? Is it possible to create user document data that can be accessed from different plug-ins like with RhinoDoc.ActiveDoc.Strings.SetString?
User data, either document, object, or attributes, is owned by a single plug-in. The plug-in is responsible for the serialization of that data.
That said, it’s possible to share user data between plug-in. Here is an example.