Create New Schema Class Dialog Box - Layout 1

Structural: The only classes that can have instances in the directory.
Abstract: Templates that are used to derive new structural classes. No object can belong only to an abstract class; each object of an abstract class also belongs to some structural subclass of that class.
Auxiliary: Contains a list of attributes. Adding an auxiliary class to the definition of a structural class or an abstract class adds the auxiliary class attributes to the definition.

Applies To: Windows Server 2008, Windows Server 2008 R2, Windows Server 2012

Item	Details
Common Name	The name that represents an object and that is used to perform searches.
LDAP Display Name	The name that is used by Lightweight Directory Access Protocol (LDAP) clients, such as the Active Directory Service Interfaces (ADSI) LDAP provider, to read and write the attribute using the LDAP protocol.
Unique X500 Object ID	The value for the governsID attribute in a classSchema object. Object identifier notation is a dotted string of nonnegative numbers, for example, 1.2.840.113556.1.5.4.
Inheritance and Type	Parent Class : A new object is defined as a subclass of its parent object. A subclass inherits structure and content rules from the parent class. The parent object becomes a superclass of the new object. Class Type : One of the following: Structural : The only classes that can have instances in the directory. Abstract : Templates that are used to derive new structural classes. No object can belong only to an abstract class; each object of an abstract class also belongs to some structural subclass of that class. Auxiliary : Contains a list of attributes. Adding an auxiliary class to the definition of a structural class or an abstract class adds the auxiliary class attributes to the definition.

Additional references