Description
Invert a local half-open window against every observed offset span, preserving multiple UTC solutions and source span indexes.
An offset maps a supplied UTC coordinate to local civil coordinates by local = UTC + offset. Half-open spans include their start and exclude their end. A forward offset jump can leave local coordinates uncovered; a backward jump can give several UTC interpretations of one local value. These tools use explicit synthetic civil-second observations rather than a named-zone database.
Invert a local half-open window against every observed offset span, preserving multiple UTC solutions and source span indexes.
When to use this tool
Use this tool to invert a local half-open window against every observed offset span, preserving multiple UTC solutions and source span indexes.
How to use the tool and how it works
- Enter spansJson, start, end using the definitions below. Serialize JSON text fields in the decoded shape shown below.
- Run the operation. Resolve input-format errors before interpreting an output.
- Read result.pieces, using the stated boundary, ordering, sign and absence conventions.
For every offset span subtract offset from the requested local window, intersect that UTC interval with the span, and return each positive piece with its source index and offset.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| spansJson | JSON array of {start,end,offset}: half-open UTC spans with local=UTC+offset, all in seconds. | Text, at most 8,192 UTF-16 code units; narrower grammar/range rules also apply. |
| start | Inclusive UTC or local window start in seconds, as explicitly stated by this operation. | Finite numeric value satisfying the stated comparisons. |
| end | Exclusive window end in seconds, on the same coordinate scale as start. | Finite numeric value satisfying the stated comparisons. |
These decoded structures show the examples inside JSON text fields. Supply their serialized JSON strings as input.
{
"spansJson": [
{
"start": 0,
"end": 10,
"offset": 0
},
{
"start": 10,
"end": 20,
"offset": 2
},
{
"start": 20,
"end": 30,
"offset": 0
}
]
}| Output field | Interpretation |
|---|---|
| result | Object containing the fields below. |
| result.pieces | Positive-length intersection pieces with the UTC/local endpoints, offsets and original indexes stated above. |
{
"input": {
"spansJson": "[{\"start\": 0, \"end\": 10, \"offset\": 0}, {\"start\": 10, \"end\": 20, \"offset\": 2}, {\"start\": 20, \"end\": 30, \"offset\": 0}]",
"start": 20,
"end": 21
},
"output": {
"result": {
"pieces": [
{
"index": 1,
"start": 18,
"end": 19,
"offset": 2
},
{
"index": 2,
"start": 20,
"end": 21,
"offset": 0
}
]
}
}
}Limitations and assumptions
- Overlapping local interpretations remain separate UTC pieces. Empty windows return no pieces.
- Span/transition coordinates are finite seconds within ±10¹² and offsets within ±86,400 seconds. Spans require start<end. No IANA database, calendar parsing, daylight-saving inference or leap seconds are included.
- Every declared outer field is required and unknown outer fields are rejected. Strings and JSON text have size limits, lists are bounded to 128 entries, and JSON nesting/node counts are bounded. Tighter operation-specific bounds stated above take precedence.
- Ordinary numeric outputs must be finite and within safe-integer magnitude. Exact large lengths/counts use decimal strings. Original record indexes and code-unit positions are zero-based; span ends are exclusive unless stated otherwise.
Alternative or Complementary methods
Keep all timestamps on one origin and in seconds, and retain gaps or competing observations. Use a maintained time-zone library when real dates, named zones or historical rules are required.
References
Similar or alternative tools
- Time Zone Local UTC Candidate List
Enumerate every offset-span UTC solution for a supplied local-second coordinate, retaining duplicates and overlapping evidence.
- Time Zone UTC Span Local Split
Intersect UTC windows with every supplied offset span and map each piece independently into local coordinates; gaps/overlaps are not concealed.