ActiveX objects within AutoCAD can expose their properties in the Property Inspector for viewing and editing. If these properties are compiled into the object’s IDL, they are automatically available to the Property Inspector. However, the Property Inspector API also provides another option for appending properties to AutoCAD objects at runtime. These runtime properties can extend any object that is found in the AcRx runtime class tree. Optionally, they can also be provided to the Property Inspector without being associated to any object.
Figure 4 - Static and dynamic properties