Description
Distinguish known zero UTC offset from unknown local offset.
A fixed UTC offset differs from a named timezone whose rules can vary by date. A zone-like label or signed-zero offset also carries metadata that a numeric minute total alone cannot express.
Distinguish known zero UTC offset from unknown local offset.
When to use this tool
Use Date: Timestamp Offset Negative Zero Check when inspecting a supplied offset or timezone annotation.
How to use the tool and how it works
- Enter offsetToken. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read result. Expand result to inspect the returned fields.
Distinguish known zero UTC offset from unknown local offset. Accept Z or ±HH:MM with bounded components; unknownLocalOffset is exact -00:00 and knownZeroOffset is Z or +00:00.1
RFC 3339 distinguishes an unknown local offset from known UTC and restricts leap-second notation to appropriate actual time contexts; lexical parsing does not verify those contexts.2
| Input field | Meaning and units | Accepted input |
|---|---|---|
| offsetToken | Offset Token | Required. Text. Implementation limit: 8192 Unicode code points and 16384 UTF-16 code units. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| result | Returned object; expand its named members below. | Required. Object. |
| result.unknownLocalOffset | True for -00:00, indicating unknown local offset under RFC 3339. | Calculated result member: boolean. |
| result.knownZeroOffset | True for recognized zero-offset spellings that do not carry the negative-zero unknown marker. | Calculated result member: boolean. |
{
"input": {
"offsetToken": "-00:00"
},
"output": {
"result": {
"unknownLocalOffset": true,
"knownZeroOffset": false
}
}
}Limitations and assumptions
- Other nonzero offsets make both flags false; no local zone or DST context is known.
- Outputs are nested inside result. Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
Alternative or Complementary methods
Use an authoritative timezone database and complete timestamp context to resolve an actual local time or day.
References
Similar or alternative tools
- Timestamp Offset Second Component Token
Parse a signed offset including seconds.
- Timezone Offset Sign Hour Minute Pair
Format offset sign, hour and minute components.