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

# Header

Header defines the metadata of the body.

## Schema ID

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

## Properties

| Title  | Property | Type                                       | Req. | Description                                                                                                                     |
| ------ | -------- | ------------------------------------------ | ---- | ------------------------------------------------------------------------------------------------------------------------------- |
| UUID   | `uuid`   | string                                     | true | Unique UUIDv1 identifier for the envelope.                                                                                      |
| Digest | `dig`    | [dsig.Digest](/draft-0/dsig/digest)        | true | Digest of the canonical JSON body.                                                                                              |
| Stamps | `stamps` | array of [head.Stamp](/draft-0/head/stamp) |      | Seals of approval from other organisations that can only be added to non-draft envelopes.                                       |
| Links  | `links`  | array of [head.Link](/draft-0/head/link)   |      | Links provide URLs to other resources that are related to this envelope and unlike stamps can be added even in the draft state. |
| Tags   | `tags`   | array of string                            |      | Set of labels that describe but have no influence on the data.                                                                  |
| Meta   | `meta`   | [cbc.Meta](/draft-0/cbc/meta)              |      | Additional semi-structured information about this envelope.                                                                     |
| Notes  | `notes`  | string                                     |      | Any information that may be relevant to other humans about this envelope                                                        |