In this chapter we've shown you how the internal
blueprint for all objects in Active Directory, known as the schema,
was derived from the X.500 directory service. We explained the
purpose of the OID numbering system and how it can be used. We then
detailed how an attribute and its syntax is structured in the schema
as attributeSchema objects, using the userPrincipalName attribute as
an example. We showed how attributes are added to classes by
detailing how classes are stored in the schema as instances of
classSchema objects. To make this clearer, we dug into the details of
the user class to see how it was constructed. Finally, we covered how
auxiliary classes can be dynamically linked in Windows Server 2003
and why it is significant.
Chapter 12 builds on what you've learned here to
demonstrate how you can design and implement schema extensions.