# Footnotes
A footnote is a piece of text that can be seen by traders in the [Trade Tariff Service](https://www.trade-tariff.service.gov.uk/footnote_search) or in their own trading software.

They do not affect how an import or export declaration is processed; they are for informational purposes. Due to this, they are subject to change at any time.

They can give additional information for traders about:

* requirements for importing or exporting a product
* how to acquire licenses or permissions
* eligibility for more favourable import fees
* suspensions of import fees and what products they apply to

A footnote's identifying fields consist of a type and a code. Footnote types are represented by 2 letters or digits. Footnote codes are 3 digits.
Footnotes are often represented as their combined identifier. For example, footnote CD491.

Footnotes have [validity dates](Data-structures;-Validity-dates.md) that represent how long the text in the footnote is accurate. The text of the footnote is contained within [description records]() that will record changes to the footnote.

Footnotes are set and owned by the teams or departments that manage the policy associated with the footnote.

```dbml
Table "Footnotes" {
  "Footnote Type ID" char(2) [primary key]
  "Footnote ID" char(3) [primary key]
  "Validity Start" date [not null]
  "Validity End" date
}

Table "Footnote Types" {
  "Footnote Type ID" char(2) [primary key]
  "Description" text
  "Application Code" char(1) [not null]
  "Validity Start" date [not null]
  "Validity End" date
}

Table "Footnote Descriptions" {
  "Footnote Type ID" char(2) [primary key]
  "Footnote ID" char(3) [primary key]
  "Validity Start" date [primary key]
  "Description" text [not null]
  "Language" char(2) [not null, default: "EN"]
}

Ref: "Footnotes"."Footnote Type ID" > "Footnote Types"."Footnote Type ID"
Ref: "Footnote Descriptions"."Footnote Type ID" > "Footnotes"."Footnote Type ID"
Ref: "Footnote Descriptions"."Footnote ID" > "Footnotes"."Footnote ID"

Table "Footnote Measure Associations" {
  "Footnote Type" char(2) [primary key]
  "Footnote Code" char(3) [primary key]
  "Measure SID" int [primary key]
  "Validity Start" date [primary key]
  "Validity End" date
}

Table "Measures" {
  "SID" int [primary key]
  "..." "..."
}

Ref: "Footnote Measure Associations"."Measure SID" > "Measures"."SID"
Ref: "Footnote Measure Associations"."Footnote Type" > "Footnotes"."Footnote Type ID"
Ref: "Footnote Measure Associations"."Footnote Code" > "Footnotes"."Footnote ID"

Table "Footnote Commodity Associations" {
  "Footnote Type" char(2) [primary key]
  "Footnote Code" char(3) [primary key]
  "Commodity Code SID" int [primary key]
  "Validity Start" date [primary key]
  "Validity End" date
}

Table "Commodity Codes" {
  "SID" int [primary key]
  "..." "..."
}

Ref: "Footnote Commodity Associations"."Commodity Code SID" > "Commodity Codes"."SID"
Ref: "Footnote Commodity Associations"."Footnote Type" > "Footnotes"."Footnote Type ID"
Ref: "Footnote Commodity Associations"."Footnote Code" > "Footnotes"."Footnote ID"

Table "Footnote Additional Code Associations" {
  "Footnote Type" char(2) [primary key]
  "Footnote Code" char(3) [primary key]
  "Additional Code SID" int [primary key]
  "Validity Start" date [primary key]
  "Validity End" date
}

Table "Additional Codes" {
  "SID" int [primary key]
  "..." "..."
}

Ref: "Footnote Additional Code Associations"."Additional Code SID" > "Additional Codes"."SID"
Ref: "Footnote Additional Code Associations"."Footnote Type" > "Footnotes"."Footnote Type ID"
Ref: "Footnote Additional Code Associations"."Footnote Code" > "Footnotes"."Footnote ID"
```

## Footnote associations

Footnotes are used to give more information about [measures](Data-structures;-Measures.md), [commodity codes](Data-structures;-Commodity-codes.md), or [additional codes](Data-structures;-Additional-codes.md). Each type has an association record type that links one footnote to one measure, commodity code or additional code. The association record is in the same [record family]() as the associated type.

The association record has its own [validity dates](Data-structures;-Validity-dates.md) so that the footnote can be attached for only a temporary period.

## Footnote types
Each footnote has a type that identifies the purpose or scope of the footnote.

Footnote types are defined by UK tariff managers and don’t come from any external source. They are created as necessary to aid categorisation and understanding.

### Existing footnote types
```sql
SELECT footnote_types.footnote_type_id AS "Type",
       footnote_types.description AS "Description",
       COUNT(version_group_id) AS "Usage count"
FROM footnotes
    INNER JOIN common_tracked_models ON footnotes.trackedmodel_ptr_id = common_tracked_models.id
    INNER JOIN footnote_types ON footnotes.footnote_type_id = footnote_types.trackedmodel_ptr_id
GROUP BY footnote_types.footnote_type_id, description
ORDER BY footnote_types.footnote_type_id
```

### Application codes
Each footnote type has an application code. The application code controls whether footnotes of that type apply to [measures](Data-structures;-Measures.md), [commodity codes](Data-structures;-Commodity-codes.md), or [additional codes](Data-structures;-Additional-codes.md).

The code also controls at what level of the commodity code hierarchy they can be placed. Some codes require that footnotes can only be attached to measures or commodities at the 8-digit commodity code level whereas others can be set at any level.

A [validation rule](Validation-rules.md) on each type enforces that footnotes are set at the correct level.

Application codes are hard-coded in systems. Changes to application codes require a change to this data standard.

|     Application code    |     Description    |     Applies to     |     What level |  Notes    |
|-|-|-|-|-|
|     1    |     Combined   nomenclature    |     Commodity   codes  | 8-digit commodity codes  | |
|     2    |     TARIC   nomenclature    |     Commodity   codes    | 10-digit commodity codes |  |
|     3    |     Export   refund nomenclature    |     ERNs  |  | ERNs are historical and are no longer used.    |
|     4    |     Wine   reference nomenclature    |     N/A   | | Wine references are historical and are no longer used. |
|    5    | Additional code | Additional codes | Any | Additional code footnotes are historical and are no longer used. |
|     6    |     CN   measures    |     Measures    | 8-digit commodity codes | |
|     7    |     Other   measures    |     Measures    | 10-digit commodity codes | |
|    8     |    Meursing heading | | | Meursing headings are historical and are no longer used. |
|     9    |     Dynamic   footnote    |     Anything   | Any |  Dynamic footnotes are historical and are no longer used.  |

## Validity rules

### Footnotes

| Code | Description |
|---|---|
| FO2 | [Uniqueness](Validation-rules;-Uniqueness.md) rule for footnote `type` and `code`. |
| FO4 | [Mandatory subrecord](Validation-rules;-Mandatory-subrecord.md) rule for footnote descriptions. |
| FO5 | [Validity contained]() rule requiring footnote validity to contain validity of any measure associations. |
| FO6 | [Validity contained]() rule requiring footnote validity to contain validity of any commodity code associations. |
| FO9 | [Validity contained]() rule requiring footnote validity to contain validity of any additional code associations. |
| FO11 | [Deletion while in use](Validation-rules;-Deletion-while-in-use.md) rule for references from a measure via a measure association. |
| FO12 | [Deletion while in use](Validation-rules;-Deletion-while-in-use.md) rule for references from a commodity code via a commodity code association. |
| FO15 | [Deletion while in use](Validation-rules;-Deletion-while-in-use.md) rule for references from an additional code via an additional code association. |
| FO17 | [Validity contained]() rule requiring footnote type validity to contain footnote validity. |

### Footnote types

| Code | Description |
|---|---|
| FOT1 | [Uniqueness](Validation-rules;-Uniqueness.md) rule for footnote `type`. |
| FOT2 | [Deletion while in use](Validation-rules;-Deletion-while-in-use.md) rule for references from a footnote. |