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

# Overview

> How ION brings inventory that already exists onto an engineering change through a reviewed change order.

<Note>
  Change orders are in beta. To try them, contact [First Resonance support](https://support.firstresonance.io).
</Note>

A **change order** applies an engineering change to inventory that already exists. Releasing a new [mBOM version](/build-hardware/bills-of-materials/versions) changes only the runs started after the release. Units already built or in progress keep the version they started against. A change order names the change, the units it applies to, and what happens to each unit's [aBOM](/build-hardware/bills-of-materials/as-built-bom), and it goes through review before ION writes anything.

A change order differs from a [redline](/build-hardware/runs-and-execution/redlines-and-deviations). A redline edits one run's steps for that build. A change order adopts a released definition across many units, and each unit keeps its own record of what changed.

## Change order types

The type sets what a change order changes. Today, ION has one type:

| Type                    | What it changes                                                      | Steps                                                                |
| ----------------------- | -------------------------------------------------------------------- | -------------------------------------------------------------------- |
| **mBOM version change** | Moves each unit's aBOM onto a released mBOM version of the same part | [mBOM change order](/build-hardware/change-orders/mbom-change-order) |

## Statuses

| Status           | Meaning                                                                                                         |
| ---------------- | --------------------------------------------------------------------------------------------------------------- |
| **Draft**        | The only editable status. You set the title, description, units in scope, and the decision for each difference. |
| **Under Review** | The content is locked. Assigned reviewers approve or reject.                                                    |
| **Approved**     | Every assigned reviewer approved. ION moves the change order here on its own. You can now apply it to units.    |
| **Completed**    | You marked the change order complete. Units still open are canceled.                                            |
| **Canceled**     | The change order stopped before any unit applied it.                                                            |

**Return to draft** takes a change order under review or approved back to **Draft** and reopens every review request, so the change order is reviewed again. **Reopen** brings a completed or canceled change order back.

## Review

A change order needs at least one reviewer before it can go for review. In the **Reviews** section of the change order, pick a role, then a user or team that holds it. You can add reviewers in **Draft** or **Under Review**, and remove them only in **Draft**. Each reviewer records **Approve** or **Reject** there, and **Reset approvals** starts the review over. Once the change order is **Approved**, the verdicts are the record of that approval and can't be changed. To review again, return the change order to draft.