Time Zones

[This is preliminary documentation and subject to change.]

Appointments are stored in the Web Store based on coordinated universal time (UTC). When you view an appointment, you need to convert the appointment to local time. Clients such as Microsoft Outlook automatically convert appointments to the local time of the client computer.

CDO automatically converts date and time values in the properties of CDO objects to local time. CDO does this based on time zone information in the corresponding CDO Configuration object. When you save an appointment or create a calendar message, CDO converts the local time specified in the StartTime and EndTime properties of the Appointment object to UTC based on the time zone information in the Configuration object. When CDO expands recurring appointments into individual instances, it uses the time zone information from the Appointment object.

Date and time values in the Fields collection and in the stream of CDO objects are converted to local time. This is done using the time zone information from the Configuration object. By default, the CDO Appointment and Configuration objects use the system time zone value from the computer that is running CDO.

For example, you are in Brussels (UTC + 1:00 hour), and you want to schedule a telephone conference with colleagues in Bangkok (UTC + 7:00 hours). You create an meeting for 9:00 A.M. local time and send a meeting request. The appointment is stored in Exchange as 08:00:00 UTC. When your colleagues view the appointment in Bangkok, their calendar client programs convert from UTC to local time and display the start time as 3:00 P.M.

You can also create floating appointments. Floating appointments are appointments that are not adjusted for time zones. For example, you may want to have an appointment on your calendar for lunch everyday from 12:00 noon to 1:00 P.M., regardless of the time zone. You would not want lunch to convert from noon to 6:00 P.M. when you travel from Brussels to Bangkok.