[xwiki-users] LDAP Authentification in multi-wiki environment

Hi, In the documentation page (http://platform.xwiki.org/xwiki/bin/view/AdminGuide/LDAPAuthenticationU seCases <http://platform.xwiki.org/xwiki/bin/view/AdminGuide/LDAPAuthenticationU seCases> ) there is an explanation for "I'm in multiwiki environment and I want my LDAP users to registered only on main wiki" That's what I've done by default on our environment. But I wonder if it's possible to do otherwise ? What is the advantage to configure ldap both in main wiki and subwikis ? What is the risk ? Thank you ? Nicolas