A custom object is a type of object created by an ObjectARX® (AutoCAD Run-Time Extension) application, which typically has more specialized capabilities than standard AutoCAD LT objects. Custom objects include parametric solids (AutoCAD® Mechanical), intelligently interactive door symbols (AutoCAD® Architecture), polygon objects (AutoCAD® Map 3D), and associative dimension objects (AutoCAD and AutoCAD LT).
A proxy object is a substitute for a custom object when the ObjectARX application that created the custom object is not available to AutoCAD LT or other host applications. Later, when the application is available, the proxy object is replaced by the custom object.
Proxy objects have significantly reduced capabilities compared to their corresponding custom objects. The extent to which proxy objects can be edited is determined by the parent ObjectARX application. For example, operations such as erasing and moving an object, or changing object properties, may or may not be possible on a proxy object, depending on the application that created it.
When you open a drawing, you might see a Proxy Information dialog box. The dialog box tells you the total number of proxy objects in the drawing (both graphical and nongraphical) and the name of the missing application and provides additional information about the proxy object type and display state. You can use the dialog box to control the display of proxy objects.
If the ObjectARX application is not installed on your system, you can check for available Object Enablers on the Web. For example, if you receive a drawing that contains objects that were created in AutoCAD Architecture, but you don't have that application installed on your system, the AEC Object Enabler is downloaded so you can view those drawings as they were intended. To control whether the program checks for Object Enablers, use the Live Enabler settings on the System tab of the Options dialog box.
For a complete list of the currently available Object Enablers, go to the Autodesk Web site at http://www.autodesk.com/enablers.
If an application such as AutoCAD® Map 3D was used to add a feature (object) classification to an object, you can view the classification in the Properties palette in the Class Name entry. If the object's classification is missing from the associated classification (XML) file, or if the associated classification file is missing, an exclamation mark is displayed in the Class Name entry. For information about what is required to create a feature classification, see the AutoCAD® Map 3D documentation.