> ## 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.

# Stamp

Stamp defines an official seal of approval from a third party like a governmental agency or intermediary and should thus be included in any official envelopes.

## Schema ID

`https://gobl.org/draft-0/head/stamp`

## Properties

| Title    | Property | Type                        | Description                                                                     |
| -------- | -------- | --------------------------- | ------------------------------------------------------------------------------- |
| Provider | `prv`    | [cbc.Key](/draft-0/cbc/key) | Identity of the agency used to create the stamp usually defined by each region. |
| Value    | `val`    | string                      | The serialized stamp value generated for or by the external agency              |

## Validation Rules

| Field | Test                                                                  | Validation Code / Message                            |
| ----- | --------------------------------------------------------------------- | ---------------------------------------------------- |
| `prv` | <ul class="gobl-test"><li class="gobl-test-present">Present</li></ul> | `GOBL-HEAD-STAMP-01`<br />Stamp provider is required |
| `val` | <ul class="gobl-test"><li class="gobl-test-present">Present</li></ul> | `GOBL-HEAD-STAMP-02`<br />Stamp value is required    |