Classes and attributes are schema objects. Each schema object can be referenced in several ways:
Active Directory Schema and other Windows 2000 administrative tools display the LDAP display name of objects. Programmers and system administrators use the LDAP display name to reference the object programmatically. This name is guaranteed to be unique for each object.
The LDAP display name usually consists of two or more words combined. When the name consists of multiple words, the subsequent words in the name are identified using capitalization. For example, the LDAP display names of two attributes are mailAddress and machinePasswordChangeInterval. For more information about LDAP, see the Internet Engineering Task Force Web site. Web addresses can change, so you might be unable to connect to the Web site or sites mentioned here.
The common name is a slightly more "friendly" version of the LDAP display name. It is also guaranteed to be unique. The common names of the two attributes used in the previous example are SMTP-Mail-Address and Machine-Password-Change-Interval.
An object's object identifier is a number issued by an issuing authority such as the International Organization for Standardization (ISO) and the American National Standards Institute (ANSI). For example, the object identifier for the SMTP-Mail-Address attribute is 1.2.840.113556.1.4.786. Every object identifier is guaranteed to be unique.
To help standardize schema naming conventions, Microsoft requires anyone extending the schema to adhere to naming rules for both the LDAP-Display-Name and the Common-Name. Naming rules are a Windows 2000 certification requirement for applications that extend the schema. For detailed information regarding these naming rules, please see the Active Directory chapter of the Windows 2000 Logo document.
For more information about schema object naming rules, see The Active Directory Programmer's Guide at the Microsoft Web site. For basic information about the schema, see Active Directory Schema overview