# Linked Identifier data (CSV) attributes

This section provides the following information about each attribute of the CSV product: 

### Name and Description

The name of the attribute and what it is describing.

### Type

The nature of the attribute, for example a numeric value or a code list value.

### Multiplicity

Describes how many times this element is expected to be populated in the data. An attribute may be optional or mandatory; these are denoted by:

* ‘1’ – Mandatory - There must be a value.
* ‘0..1’ – Optional – If populated a maximum of one attribute will be returned. These values may be used in combination.

## Linked Identifier data attributes <a href="#bookmark3" id="bookmark3"></a>

### RELATIONSHIP\_ID

Unique identifier for the relationship. Made up of a concatenated string in the format: {Data Identifier 1}*{Feature Identifier 1}*{Data Identifier 2}*{Feature Identifier 2}*{CorrelationType Number}

* **Type**: text
* **Multiplicity**: \[1]

### IDENTIFIER\_1

The primary identifier of Source Dataset 1.

* **Type**: text
* **Multiplicity**: \[1]

### VERSION\_NUMBER\_1

Version number of the primary identifier of Source Dataset 1. Where available, NULL otherwise.

* **Type**: integer
* **Multiplicity**: \[0..1]

### VERSION\_DATE\_1

Version date of the primary identifier of Source Dataset 1. Where available, NULL otherwise.

* **Type**: date time
* **Multiplicity**: \[0..1]

### IDENTIFIER\_2

The primary identifier of Source Dataset 2.

* **Type**: text
* **Multiplicity**: \[1]

### VERSION\_NUMBER\_2

Version number of the primary identifier of Source Dataset 2. Where available, NULL otherwise.

* **Type**: integer
* **Multiplicity**: \[0..1]

### VERSION\_DATE\_2

Version date of the primary identifier of Source Dataset 2. Where available, NULL otherwise.

* **Type**: date time
* **Multiplicity**: \[0..1]

### CONFIDENCE

Confidence value based on a comparison of feature dates between the two source features. Can be one of:

* Version information is correct
* Version information has potentially changed
* Version information has changed
* **Type**: text
* **Multiplicity**: \[1]
* **Notes**: May be a constant value of the possible ones for certain relationships.


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.os.uk/os-downloads/products/buildings-and-infrastructure-portfolio/os-open-linked-identifiers/os-open-linked-identifiers-technical-specification/linked-identifier-data-csv-attributes.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.