# Global ID & Link Fields on Object Records & Documents

Global ID and link fields allow you to keep track of object records and documents when implementing external and/or Vault-to-Vault integrations.

## Global ID Fields

Global ID fields are universal identifiers that allow you to keep track of and reference object records, documents, and document versions in external and Vault-to-Vault integrations. This can be useful when copying documents and object records from one Vault to another or maintaining a single identifier for a document or object record between Vault and an external system.

### Global ID Fields

<table class="wbord">
  <tr>
    <td>
      <p>
        <strong>Field</strong>
      </p>
    </td>
    <td>
      <p>
        <strong>Description</strong>
      </p>
    </td>
    <td>
      <p>
        <strong>Entity</strong>
      </p>
    </td>
  </tr>
  <tr>
    <td>
      <p>
        <em>global_id__sys</em>
      </p>
    </td>
    <td>
      <p>
        Combination of the Vault ID and the Document ID. Read-only.
      </p>
    </td>
    <td>
      <p>
        Document
      </p>
    </td>
  </tr>
  <tr>
    <td>
      <p>
        <em>global_version_id__sys</em>
      </p>
    </td>
    <td>
      <p>
        Combination of the Vault ID and the document version's Global ID. Read-only.
      </p>
    </td>
    <td>
      <p>
        Document
      </p>
    </td>
  </tr>
  <tr>
    <td>
      <p>
        <em>global_id__sys</em>
      </p>
    </td>
    <td>
      <p>
        Combination of the Vault ID and the object record's ID. Read-only.
      </p>
    </td>
    <td>
      <p>
        Object Record
      </p>
    </td>
  </tr>
</table>

## Link Fields {#link-fields}

Link fields allow you to track the source of object records or documents that are brought into your Vault whether from an external source or a Vault-to-Vault integration.

### Link Fields

<table class="wbord">
  <tr>
    <td>
      <p>
        <strong>Field</strong>
      </p>
    </td>
    <td>
      <p>
        <strong>Description</strong>
      </p>
    </td>
    <td>
      <p>
        <strong>Entity</strong>
      </p>
    </td>
  </tr>
  <tr>
    <td>
      <p>
        <em>link__sys</em>
      </p>
    </td>
    <td>
      <p>
        Default value is null. Used to store a value that identifies a document's content. For example, the document's <em>global_id__sys</em> field value.
      </p>
    </td>
    <td>
      <p>
        Document
      </p>
    </td>
  </tr>
  <tr>
    <td>
      <p>
        <em>version_link__sys</em>
      </p>
    </td>
    <td>
      <p>
        Default value is null. Used to store a value that identifies a document version's content. For example, the document version's <em>global_version_id__sys</em> field value.
      </p>
    </td>
    <td>
      <p>
        Document
      </p>
    </td>
  </tr>
  <tr>
    <td>
      <p>
        <em>link__sys</em>
      </p>
    </td>
    <td>
      <p>
        Default value is null. Used to store a value that identifies an object record across Vaults. For example, an object record's <em>global_id__sys</em> field value.
      </p>
    </td>
    <td>
      <p>
        Object Record
      </p>
    </td>
  </tr>
</table>

All global ID and link fields are retrievable via VQL and Vault API queries.

[1]: #link-fields