Hi CADtag. We are really not too far apart in our thinking. We are using the same concepts but you focus more on the detailed description of the object (perhaps for some degree of BIM) while I focus more on the control of layers for viewing and plotting (the outcome being easier and faster drafting and plotting).

The strong point of the example I gave is that it allows objects relating to different construction stages, drawing-types, view-points and view-IDs to be classified and displayed separately from each other while being placed correctly in relation to each other in the same model-space. I struggled for a long time with the aspect of object-code and eventually decided that for architecture a high degree of refinement was not needed, particularly since consultant models are most likely to be included in an architect's drawing by Inserting or Attaching. BIM is not really an option in 2D models that cannot fully show the vertical component such as would be produced by say a piping program.

A brief explanation of the Drawing-type code: Up to nine different drawing types can be included in the one model by creating a three digit number code that is the sum of relevant individual drawing codes. Thus a wall that is required in every drawing type would have the sum of all the codes i.e. 511 whereas electrical would have 064 and thus appear only in the electrical drawing.
Sounds complicated but it is all managed by automatic functions for both creation and viewing of layer combinations.

Thanks for your input. You have helped me to clarify my thinking about the logic of the system.