> ## Documentation Index
> Fetch the complete documentation index at: https://developer.ammdistro.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Identifiers

> Your IDs, UPCs, ISRCs and the other codes the API accepts.

## Your IDs

| ID | Where | Format |
| - | - | - |
| Release ID | The `{releaseId}` in the URL | 1 to 128 letters, digits, `.`, `_`, `:` or `-`. Unique per account. |
| Track ID | `tracks[].externalId` | Same format. Unique within the release. |
| Transfer ID | `transfer.batch` and `{transferId}` | Same format. Unique per account. |

AMM Distro also returns its own `id` for each release and track. You don't need it for any request.

## UPC

12 digits (UPC-A) or 13 digits (EAN-13), with a valid check digit. Spaces and hyphens are removed.

* **New release:** optional. Leave it out and one is assigned when the release is approved.
* **Catalog transfer:** required, and must be the release's existing UPC.

A UPC already used by another release on AMM Distro, outside your account, is refused with `409 upc_in_use`.

## ISRC

12 characters: country code, registrant code, year and number, such as `USRC17607839`. Hyphens and lower case are accepted (`us-rc1-76-07839`).

* **New recording:** optional. Leave it out and one is assigned when the release is approved.
* **Catalog transfer:** required on every track, and must be the recording's existing ISRC.
* **The same recording on two releases** (a single and its album): use the same ISRC on both.

No two tracks in one release can share an ISRC. An ISRC that belongs to a recording outside your account is refused with `409 isrc_in_use`.

## Other codes

| Code | Field | Format |
| - | - | - |
| ISWC | `tracks[].iswc` | `T` followed by 10 digits, such as `T1234567890` |
| IPI | `credits[].ipi` | 9 to 11 digits |
| Spotify artist ID | `artists[].spotifyId` | 22 letters and digits, from the artist's Spotify URL |
| Apple Music artist ID | `artists[].appleMusicId` | Digits, from the artist's Apple Music URL |


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