AD is at 2003 functional level, some of our DC's are running Windows Server 2003, some are 2008, some are 2008 R2.

When using the following query:

(objectCategory=user)

I do not expect to see any result where the objectCategory attribute is equal to 'CN=Person,CN=Schema,CN=Configuration,DC=Contoso'

I expect only objects where the objectCategory attribute is equal to 'CN=User,CN=Schema,CN=Configuration,DC=Contoso'

However, the query does indeed return all objects with the objectCategory attribute equal to 'CN=Person,CN=Schema,CN=Configuration,DC=Contoso'

My question then is this: Why do I see the search results that I do? Does AD actively translate queries that include (objectCategory=user) to (objectCategory=Person)? I have looked at the schema definitions for both the Person and the User class, but I cannot see any reason for the query results as I am experiencing them. I know that the User class is a subclass of the organizationalPerson class, which is a subclass of Person, but I can't see an attribute value that would explain this translation.