> ## Documentation Index > Fetch the complete documentation index at: https://help.ammdistro.com/llms.txt > Use this file to discover all available pages before exploring further. # Previously released music, ISRCs and UPCs > An ISRC identifies a single recording, and a UPC identifies a release. An **ISRC** identifies a single recording, and a **UPC** identifies a release. You don't need either to release new music: we assign them for free when your release is approved. If a track is already out somewhere, mark it **Previously released** and enter its existing ISRC so its streams stay linked. ## What ISRCs and UPCs are * **ISRC** (International Standard Recording Code): one per recording, for example `QT8JA2500001`. Stores use it to count streams and connect the same recording across releases. A recording keeps the same ISRC wherever it appears. * **UPC** (Universal Product Code): one per release, a 12- or 13-digit barcode number. It identifies the single, EP or album as a product. ## New music Leave each track set to **New recording**. When your release is approved, we assign an ISRC to every track that doesn't have one, and a UPC to the release. You'll see them on the release page afterwards. An ISRC we assigned shows as locked in the builder: "Assigned by us and registered to this recording." ## Music that's already out If the release came out before, answer **Released before?** in the **Release** section with **Yes, it's been released**, then add the **Original release date** and the **Previous distributor or platform** (for example another distributor, or SoundCloud if you released it yourself). The **Release date** field then becomes the day it's available again; stores keep showing the original release date. You can also leave it as **As soon as possible**, so it goes back in stores the day it's approved. If a track was released before, with us or anywhere else, use its existing ISRC. 1. Open the track in the builder. 2. Under **Previously released**, choose **Previously released**. 3. Enter the ISRC in the **ISRC** field. ![The Previously released switch with the ISRC field and the option to reuse a recording](https://ammdistro.com/helpdesk/distro-builder-previously-released.webp) If the recording is already on AMM Distro, click **Or reuse a recording already on the platform** instead. See **Single, EP or album?** for how this works. A previously released track can't be approved without its ISRC. ### Where to find your ISRC * Your old distributor's dashboard usually lists the ISRC for each track. * In Spotify for Artists or Apple Music for Artists, look at the song's details. ### ISRC format An ISRC is 12 characters: 2 letters for the country, 3 letters or numbers for the registrant, then 7 digits. You can type it with or without hyphens. If it doesn't fit this format, you'll see "Invalid ISRC format." ## Moving a whole release from another distributor Use **Catalog Transfer**. It copies the ISRCs, the UPC and the original release date for you and marks the tracks as previously released. See **Move your catalog from another distributor**. ## When an ISRC is locked If an ISRC has already been delivered to stores, the recording's details, credits and audio are locked: "This ISRC is already distributed. Recording metadata, credits, and masters are locked so every product stays identical." This keeps the same recording identical on every release it appears on. ## Common questions ### Can I use my own UPC? The builder doesn't have a UPC field for new releases. If you're moving a release from another distributor, Catalog Transfer keeps its UPC. ### Does the ISRC change if I put a single on an album? No. Reuse the recording on the album so it keeps the same ISRC and its streams stay together. ### Is a sped-up or remixed version the same ISRC? No. A different version is a different recording, so it needs its own ISRC. Leave it as **New recording** and we'll assign one. ### I entered the wrong ISRC. Fix it in the builder before you submit. If it's locked, send us a message from the chat on this page, or email [team@ammdistro.com](mailto:team@ammdistro.com). **Related:** [Move your catalog from another distributor](https://help.ammdistro.com/getting-started/move-your-catalog-from-another-distributor.md) · [Single, EP or album?](https://help.ammdistro.com/creating-a-release/single-ep-or-album.md) · [Audio requirements](https://help.ammdistro.com/creating-a-release/audio-requirements.md) · [Check and submit your release](https://help.ammdistro.com/creating-a-release/check-and-submit-your-release.md) This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.