Attaching Extended Entity Data to an AutoCAD Object

Extended entity data is attached to an object's definition data using the DXF codes 1000 – 1071. Because of the limited range of these DXF codes and the fact that xdata can be set by any application, Autodesk has devised a method to keep this information is unique to a particular program. This reduces the possibility of information stored by one program affecting the data or even the operations of other applications. AutoCAD requires that all extended entity data be assigned an application name. That application name may only be used once in a drawing. This helps ensure that information assigned by more than one program to the same AutoCAD entity is unique as long as the application names used by these programs are different.