In general, AttributeSelection is the set of attributes is a list of zero or more Attribute-Names for the attributes to return.
Attributes are returned at most once in an entry. If an attribute description is named more than once in the list, the subsequent names are ignored. If an attribute description in the list is not recognized, it is ignored by the server.
If no Attribute-Names are specified, then all user attributes and no Operational Attribute will be returned.
Client implementers should note that even if all user attributes are requested, some attributes and/or attribute values of the entry may not be included in Search results due to access controls or other restrictions. Furthermore, servers will not return Operational Attributes, such as objectClasses or attributeTypes, unless they are listed by name. OR one of the attributeSelectors are used.