Calling OS X Functions
Open Directory plug-ins can call any OS X function but to reduce memory usage and make porting to other platforms easier, Open Directory plug-ins should restrict themselves to the System and CoreFoundation frameworks and use other frameworks only when there is a compelling reason to do so. (For example, the Open Directory LDAP plug-in uses the LDAP library.)
Open Directory plug-ins themselves should not display any human interface (HI). Only a plug-in’s separate configuration application or Directory Access plug-in should display HI.