> ## Documentation Index
> Fetch the complete documentation index at: https://docs.gobl.org/llms.txt
> Use this file to discover all available pages before exploring further.

# Period

Period represents two dates with a start and finish.

## Schema ID

`https://gobl.org/draft-0/cal/period`

## Properties

| Title | Property | Type                          | Description                                                           |
| ----- | -------- | ----------------------------- | --------------------------------------------------------------------- |
| Label | `label`  | string                        | Label is a short description of the period.                           |
| Start | `start`  | [cal.Date](/draft-0/cal/date) | Start indicates when this period starts.                              |
| End   | `end`    | [cal.Date](/draft-0/cal/date) | End indicates when the period ends, and must be after the start date. |

## Validation Rules

| Field                 | Test                                                     | Validation Code / Message                                         |
| --------------------- | -------------------------------------------------------- | ----------------------------------------------------------------- |
| <small>Period</small> | <ul class="gobl-test"><li>End not before start</li></ul> | `GOBL-CAL-PERIOD-10`<br />End date must be on or after start date |
| `start`               | <ul class="gobl-test"><li>Not zero</li></ul>             | `GOBL-CAL-PERIOD-01`<br />Start date cannot be zero               |
| `end`                 | <ul class="gobl-test"><li>Not zero</li></ul>             | `GOBL-CAL-PERIOD-02`<br />End date cannot be zero                 |