Using Base Object Classes
Concept Procedure Quick Reference

You can create hierarchies of object classes. When you base a new object class on an existing object class, the new object class has all the properties of the base class.

You cannot change base properties, but you can modify their attributes, including the default value and the range of allowable values, and you can include additional properties.

Note To define an object class, you must have Alter Object Class privileges.

Sample Use

  1. Define an object class called Roads with the basic properties that you want to assign to all roads.
  2. Define object classes called Primary Roads, Local Roads, and Fire Roads, and base each of them on Roads.

    Because the new object classes are based on Roads, they include all the properties selected for Roads.

    When you select all objects in a base class, objects in object classes based on that class are also selected.

Using Object Classes as Base Classes Only

Sometimes when you create a base class, you intend to use it only as a base for other object classes and not to create objects in drawings. For example, you may not want the to use the Roads object class to create roads. You want people to create roads using the Primary Roads and Secondary Roads classes that are based on the Roads class. You can specify that an object class can be used only as a base class.

Editing Base Classes

To edit a definition for an object class, you must have a sample object in the drawing. However, if you use an object class as a base class only, you will not have any example objects. For these object classes, you must edit the .xml definition file directly.

See Also