Sun said it will take an “aggressive” approach to opening up the source code of its core operating system. It just isn’t saying when. The Santa Clara, Calif.-based network computer maker fended off questions from reporters and analysts Tuesday during a briefing centered on the major developments for Solaris 10. The enterprise platform is scheduled for a September 2004 launch date to coincide with the shipment of Sun’s next generation Java Enterprise System. Update: More here.