Facebook yesterday issued a fix affecting the times and dates of events created by third party Facebook apps. The fix means app developers can now specify times for events either in their local time zone or in PST (Pacific Standard Time).

Drew Hoskins, a developer at Facebook, said on a Facebook developer blog, “If you input times without a time zone, they will be passed directly and stored as a timestamp based on Facebook’s servers’ time. If you explicitly mark your time as UTC, it will be converted to Facebook time and stored in PST.”

(Update Jan 2011) Hoskins recommends events are created using ISO format timestamps and without any timezone information. In this way people viewing the event using Facebook will see the correct start and end times. (/update)

The developer community is busy figuring out which option works best for individual apps. However, the bug fix came as something of a surprise to some developers. One developer commenting on the Hoskins blog said, “A change was just made that affected apps. We used to use UTC + an offset based on whether it was DST or not. That offset is now cut in half. Please [let us know] before any changes are made.”