Description
Parse a four-digit nonzero-leading first year, slash, and a two- or four-digit second year.
Calendar coordinates depend on an era, origin, day-start rule, and sometimes an arithmetic rather than observational convention. A supplied coordinate difference does not resolve those choices.
Parse a four-digit nonzero-leading first year, slash, and a two- or four-digit second year.
When to use this tool
Use Historical Date Double Year Token when you need a documented calendar convention or source-coordinate comparison.
How to use the tool and how it works
- Enter token. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read firstYear, secondYear, consecutive. Inspect consecutive before interpreting the associated values.
Parse a four-digit nonzero-leading first year, slash, and a two- or four-digit second year. Expand a two-digit suffix into the same century or the next when needed, then report whether years are consecutive.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| token | Text in the explicitly supported lexical grammar. | Required. Text; maximum UTF-16 length 8192. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| firstYear | First Year | Required. Safe integer. |
| secondYear | Second Year | Required. Safe integer. |
| consecutive | Consecutive | Required. Boolean. |
{
"input": {
"token": "1699/00"
},
"output": {
"firstYear": 1699,
"secondYear": 1700,
"consecutive": true
}
}Limitations and assumptions
- A match does not require consecutiveness; the parser does not resolve old-style/new-style calendars, historical year starts, or an authoritative date interpretation.
- 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
Consult the source calendar and authoritative date information for actual observance, conversion, or historical dating.
References
Similar or alternative tools
- Regnal Year Era Token
Return suppliedFirstYear+regnalYear-1 and a JSON-array key retaining source, era, and regnal year.
- Chronology Era Zero Label
Return validLabel when hasYearZero or yearLabel is nonzero.