2.1.1 [ECMA-402/2] Section 6.4.1 IsValidTimeZoneName (timeZone)
V0122: The only timeZone supported is UTC
The specification states:
6.4.1 IsValidTimeZoneName (timeZone) The IsValidTimeZoneName abstract operation verifies that the timeZone argument (which must be a String value) represents a valid Zone or Link name of the IANA Time Zone Database. The abstract operation returns true if timeZone, converted to upper case as described in 6.1, is equal to one of the Zone or Link names of the IANA Time Zone Database, converted to upper case as described in 6.1. It returns false otherwise.
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The only timeZone supported is UTC. If no timeZone is provided, UTC is assumed.