what are aliases in ldap

What are aliases in ldap (referenced for example here php.net/ldap) Are they pointers to other objects in the system not directly under the object where the alias i开发者_StackOverflows found?

There are two concepts - referrals and aliases. An alias contains the DN of another object, whereas a referral contains one or more URLs of objects. The URLs are usually, but not necessarily, LDAP URLs. The LDAP URL contains the server's host/port and an object's DN. The host/port information can point to a directory server that differs from the one that returned the referral.

An alias is dereferenced and processed by the server, whereas a referral is returned to the client, which is responsible for processing it.