[xwiki-users] How does LDAP Authentication using "xwiki.authentication.ldap.ldap_user_search_fmt" work?

Hi, can someone explain (or provide links to documentation) how XWiki's LDAP authentication using "xwiki.authentication.ldap.ldap_user_search_fmt" works? I understand, that XWiki binds using xwiki.authentication.ldap.bind_DN and xwiki.authentication.ldap.bind_pass (which are configured as static user), but how does it then continue to check the user's password against the one in the LDAP/DA? In the configuration examples I found, this parameter is usually not used, however in the old installation I'm supposed to migrate it is. I need to find out how that works, to decide if we should go on with it or no. I've had a look at some of the Java libraries (XWikiLDAPAuthServiceImpl.java and XWikiLDAPUtils.java but they didn't help me very much (not being very proficient in Java). Any hint or link to some more in-depth documentation (deeper than http://platform.xwiki.org/xwiki/bin/view/AdminGuide/Authentication but above sourcecode level) is highly appreciated. Cheers Frank