The following table lists the classes of objects defined in the Microsoft Exchange Server 5.0 directory schema. By clicking a class name in the table, you see a description of the attributes that belong to an object in that class.
In the attribute descriptions, attributes marked with an X in the Must column are required. This means that the attribute must be present on any object of this type. Function calls that attempt to create or import an object that is missing one or more required attributes will fail, as will function calls that attempt to delete a required attribute from an existing object. This requirement is enforced by the directory service agent of Microsoft Exchange Server. Required attributes are required not only on their object of origin, but also on any objects that inherit from it.