> For the complete documentation index, see [llms.txt](https://docs.internetobject.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.internetobject.org/schema-definition-language/data-types/date-and-time.md).

# Date and Time

The datetime, date, and time types.

Internet Object has three temporal types, each with its own literal value:

| Type       | Literal                    | Captures               |
| ---------- | -------------------------- | ---------------------- |
| `date`     | `d'2024-03-20'`            | calendar date          |
| `time`     | `t'14:30:45'`              | time of day            |
| `datetime` | `dt'2024-03-20T14:30:45Z'` | date + time (ISO 8601) |

> For the literal value syntax in detail, see [Date and Time](/structure-and-syntax/values/date-and-time.md).

```ruby
created: datetime, birthday: date, opensAt: time
---
~ dt'2024-03-20T14:30:00Z', d'1990-05-01', t'09:00:00'   # ✓
```

## TypeDef

These types share one TypeDef. A MemberDef accepts only the options below.

| Option     | Type     | Description                                                  |
| ---------- | -------- | ------------------------------------------------------------ |
| `type`     | string   | `datetime`, `date`, or `time`. First positional value.       |
| `default`  | datetime | Value used when the member is omitted.                       |
| `choices`  | array    | Restricts the value to a fixed set.                          |
| `min`      | datetime | Earliest allowed value (inclusive).                          |
| `max`      | datetime | Latest allowed value (inclusive).                            |
| `optional` | bool     | If `true`, the member may be omitted. Shorthand: `?` suffix. |
| `null`     | bool     | If `true`, the member may be `null`. Shorthand: `*` suffix.  |

There is deliberately **no `format` option**. For the numeric and string types a `format` selects a spelling for one unchanging value, but a date is not a datetime — the three temporal types are genuinely different, so the choice lives in the **type name**, which both constrains the value and selects its literal. See [Constraints and presentation](/schema-definition-language/advanced-schema-concepts/memberdef.md#constraints-and-presentation).

A writer therefore emits the literal matching the declared type: `date` → `d"…"`, `time` → `t"…"`, `datetime` → `dt"…"`. Where no schema applies, the kind is inferred from the value instead — see [Temporal kind](/serialization/value-formatting.md#temporal-kind).

## Constraints

### min / max

```ruby
when: { datetime, min: dt'2024-01-01T00:00:00Z', max: dt'2024-12-31T00:00:00Z' }
---
~ dt'2024-06-01T00:00:00Z'    # ✓
```

## Optional, nullable & defaults

```ruby
deletedAt?*: datetime   # optional + nullable
---
~ {}    # ✓ omitted → absent
~ N     # ✓ null
```

| Input                     | Result                                    |
| ------------------------- | ----------------------------------------- |
| valid temporal literal    | the value                                 |
| below `min` / above `max` | `mismatched-min` / `mismatched-max` error |
| `N`, nullable (`*`)       | `null`                                    |
| `N`, not nullable         | `forbidden-null` error                    |
| omitted, optional (`?`)   | absent                                    |
| omitted, required         | `missing-value` error                     |

## See Also

* [Date and Time (value syntax)](/structure-and-syntax/values/date-and-time.md)
* [TypeDef](/schema-definition-language/advanced-schema-concepts/typedef.md) · [MemberDef](/schema-definition-language/advanced-schema-concepts/memberdef.md)


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