Basically, you can add your own ‘dictionaries’ to entities endlessly, but right now, you need to dive into ruby.
In fact, almost every extension adds ‘data’ this way.
There are a few basic dictionaries, Geolocation, 3D warehouse, advanced Attributes and Dynamic Components are the most obvious, there might be more.
Way’s to add data through extensions:
IFC-manager (property sets!)
Quantifier Pro:
Check this thread as well:
Right now, the way to add data through IFC or other classifications (the original tags in SketchUp) only works if you use an extension. To create your own classification is a lot of work and the data does not get transported when exported (thus another extension is needed…)