220.127.116.11.8 Effects of Defunct Attributes and Classes
If the forest functional level is DS_BEHAVIOR_WIN2003 or greater:
Instances of a defunct attribute cannot be read.
Instances of a defunct class can be read using the filter term (objectClass=*).
When reading any OID-valued attribute that contains identifiers for schema objects, if the attribute identifies a defunct schema object, the read returns an OID (the attributeID if an attribute, the governsID if a class) not a name (the lDAPDisplayName of an attribute or class). This behavior applies to the mustContain, systemMustContain, mayContain, systemMayContain, subClassOf, auxiliaryClass, and possSuperiors attributes of schema objects (that is, attributeSchema or classSchema objects that are located in the schema NC). This behavior also applies to the objectClass attribute of all other objects.