If dev-lang/php (-5.4.20) is compiled without calendar-USE-flag sync is with e.g. "CalDAV-Sync" (www.dmfs.org) not possible. Error by app is 500 - Internal Server Error. apache-error-log: Tue Oct 15 16:22:50 2013] [error] [client x.x.x.x] PHP Fatal error: Call to undefined function cal_days_in_month() in /var/www/localhost/davical/inc/RRule-v2.php on line 909
davical-1.1.1-r1 has dev-lang/php[calendar] in its dependency.