About access control of LDAP

[Wenxiao.guo [郭文孝] <Wenxiao.guo@mic.com.tw>]

Hi!
Access Entity Specifiers:
       Specifier                    Entities
*                           ----         All, including anonymous and
authenticated users
anonymous       ----         Anonymous(non-authenticated) users
users                  ----        User associated with the target entry.
self                      ----        User associated with target entry.
dn=<regex>       ----        Usera matching regular expression

I don't understand  what are the "users", "self", "dn=<regex>"?  When the
identification of LDAP client is user, self or dn=<regex>  ?
 Who can give me answer/examples.?

Thanks