Unable to add IANA timezones as they are not present in the ‘Available’ list
Wherever users have a choice of time zone, the choices are populated using the Time Zone choice list on the User [sys_user] table. Not all time zones appear by default.
About this task
To add or remove time zones from the list of time zones:
1. Navigate to User Administration > Users and open any user record, or click New.
2.Right-click Time zone, and then select Personalize Choices.
3. Highlight the desired time zone from the ‘Available’ or ‘Selected’ lists, and then Add or Remove the time zones as needed.
4. If the timezone does not appear in the ‘Available’ list, then search in ‘Enter new item’ and then click Add
It will add the timezone in the selected list
Note: The time zone choice MUST be equal to a valid Java/IANA time zone name. If it is not, then the time zone choice is effectively UTC/GMT
Service Now supports all the Java/IANA timezones