# Time: boundaries

What the construct does NOT do: limits, reserved values, neighbouring constructs and the selection rule.

## Does not do

- **Not read the system clock.** No axis is taken from the machine clock:
  the case sets `decision_time`, `knowledge_time`,
  `legal_time` and `timezone` explicitly, the scenario test — one per scenario.
  "Today" in a case is a date, not a call.
- **Not add dates to magnitudes.** `Date + Quantity` does not exist:
  a period is only a period step, a duration only a duration
  measurement. `N months` / `N years` are `Quantity` with a unit, not
  added to a date.
- **Not measure months and years.** `days_between` is calendar days
  (`Integer`, sign by argument order); hours and minutes —
  `hours_between`/`minutes_between` over `Instant`. Months and years
  are built by the period step, not measured.
- **Not cover what time does not formalize.** Closure also carries
  a window: outside the window it produces no negative — a repealed
  registry does not prove "no licence".
- **Not execute time `@id`.** Dates have no separate identity:
  identity belongs to editions and events; time is a value.

## Reserved and closed

- `during`, `overlaps`, `before`, `after` — RESERVED predicates
  (`LDC-E2102`).
- `Duration`, `CalendarPeriod`, `BusinessPeriod` — types without a constructor:
  a value comes only from measurement or a period step.
- `Date` without a timezone policy in an event — fatal
  `TEMPORAL_RESOLUTION_POLICY_MISSING`, not silent UTC:
  the zone choice changes event order and window hits.
- Event `time` precision is a microsecond: rounding to a second
  is forbidden; fractions of a second tell events and identity apart
  (`EVENT_ID_CONFLICT`).

## Neighbours and the selection rule

- `effective` vs target `window`: norm applicability vs performance
  period. See the selection table in `README.md`.
- `effective` vs edition anchor: the rule's own date vs the act's date.
- `days_between` vs period step: measure a duration vs build
  a period (months/years).
- `Date` vs `Instant`: civil date vs offset instant; comparisons stay within kind.
- Fact-date comparison vs `governs`: case surface (corpus) vs
  JSON transport of the axis.