W.r.t timezone update for Asia/Choibalsan

Hi, I am currently updating the timezones for evolution (default mail client for many linux distros) . I have a small doubt with updating timezone for the location Asia/Choibalsan. I see that the offset is +09000 from the olson timezone database (ftp://elsie.nci.nih.gov/pub/) for the standard timezone, but timeanddate.com (http://timeanddate.com/worldclock/results.html?query=Choibalsan), http://www.travelpost.com/AS/Mongolia/Dornod/Choibalsan/7449157 and http://www.timeinside.com/view.jsp?region=Asia&country=Mongolia&city=Choibal... show its +08000 for Choibalsan. Please let me know which would be the right offset for Asia/Choibalsan. thanks in advance, Chenthill.