| UUID | uuid | string | | Universally Unique Identifier. |
| Type | type | cbc.Key | | Type of the document referenced. |
| Issue Date | issue_date | cal.Date | | IssueDate reflects the date the document was issued. |
| Series | series | cbc.Code | | Series the referenced document belongs to. |
| Code | code | cbc.Code | true | Source document’s code or other identifier. |
| Currency | currency | currency.Code | | Currency used in the document, if different from the default currency. |
| Lines | lines | array of integer | | Line index numbers inside the document, if relevant. |
| Identities | identities | array of org.Identity | | List of additional codes, IDs, or SKUs which can be used to identify the document or its contents, agreed upon by the supplier and customer. |
| Period | period | cal.Period | | Tax period in which the referred document had an effect required by some tax regimes and formats. |
| Reason | reason | string | | Human readable description on why this reference is here or needs to be used. |
| Description | description | string | | Additional details about the document. |
| Stamps | stamps | array of head.Stamp | | Seals of approval from other organisations that may need to be listed. |
| URL | url | string | | Link to the source document. |
| Tax | tax | tax.Total | | Tax total breakdown from the original document in the provided currency. Should only be included if required by a specific tax regime or addon. |
| Extensions | ext | tax.Extensions | | Extensions for additional codes that may be required. |
| Meta | meta | cbc.Meta | | Meta contains additional information about the document. |
