How to add Time Zones that do not come included in the user preference 'Time zome' dropdown.
ServiceNow only supports the Java-supported timezones. Please review the doc below.
If you need to add a timezone that does not exist. You will need to find an existing timezone in the choices of the sys_user.time_zone field and update the Label.
Example: Let's say you want to add Pakistan (which is GMT+5) to the user preference dropdown list. You will need to go to the choices of the sys_user.time_zone field and find an existing timezone record which is in the GMT+5 timezone (Antarctica/Mawson is the same timezone as Pakistan (GMT+5)). In this case, the Antarctica/Mawson timezone is in the same timezone as Pakistan. You have two options.
1. You can rename the Label of Antarctica/Mawson to Pakistan (be sure to keep the Value field the same, do not change the Value field, leave it as Antarctica/Mawson because this is the supported java time).
2. Or, you can create a new record just like Antarctica/Mawson and update the Label for the new record to Pakistan (this way you would have a timezone for Antarctica/Mawson and Pakistan).