Lets imagine to have a structured entity of parts. How can we have in TOP a selection of graphical entities which represent pneumatic, electronic, mechanic and hydraulic elements? Create many sub-parts for each part that represents a component of my entity. To create many parts for graphic use can slow down the part’s structure management and interfere with the data management.

Another typical situation is related to the part display management. A problem difficult to solve with TOP. You can create sub-parts, but, as in the previous case, a problem arises to mix parts which represent the object to be displayed with parts necessary to select certain geometries. It is not always easy to manage with TOP the selection of balloons, axis, and dimensions. In certain cases the AutoCAD filters can be used, but not always.