Functions
ISZONED
TRUE if the value is a zone-aware instant
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When to use it
When should I use ISZONED instead of just calling a timezone function directly?
Use ISZONED to guard a formula that may receive either a plain date serial or a zoned instant, so you can branch logic and avoid passing an unzoned value to a function like TZCONVERT that requires a zoned input.
What does ISZONED return for a plain number or a text string?
ISZONED returns FALSE for plain numbers, text, dates created without a timezone, and errors — only values produced by TZDATETIME, TZCONVERT, or similar zone-aware functions return TRUE.
Can I use ISZONED to validate user-provided values before further timezone calculations?
Yes. Wrap ISZONED in an IF to detect whether a value is zone-aware and fall back to a safe default or localization step when it is not.
Use cases
Branch logic based on whether a value is zoned
Confirm a localized instant is recognized as zoned
Used in
engineering · operations · finance
Syntax
ISZONED(value)