Schema 

A set of rules that describes the nature of data is stored. Schemas helps maintain consistency and quality data, and reduces duplication of data. The object class attribute determines the schema rules an entry must follow. Schemas define the following: 

• Required attributes

• Allowed attributes

• The method to compare attributes

• Limits to what the attribute can store (for example, restricting the attribute to an integer)

• Restrictions on what information is stored (prevents duplication)

Attribute Abbreviation 

The following are common attribute abbreviations used in LDAP: 

• User id : uid

• Common Name ; cn

• Surname : sn

• Location : l

• Organizational Unit : ou

• Organization : o

• Domain Component : dc

• State : st

• Country : c

• Street address : street

Search Filters 

Criteria for attributes that must satisfy for an entry to be returned. Search filters typically use a base DN, which is the base object entry the search is relative to. They also use prefix notations. LDAP uses the following standards: 

• LDAP String Representation of Search Filters

• LDAPv3 Search Filters

The following search operators are supported: 

• AND : &

• OR : |

• NOT : !

• Approximately equal : ~=

• Greater than or equal : >=

• Less than or equal : <=

• Any : *

Below are some examples of search filters: 

(objectclass=posixAccount)

(cn=Mickey M*)

(|(uid=fred)(uid=bill))

(&(|(uid=jack)(uid=jill)(objectclass=posixAccount))