> ## 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.

# Manufacturing BOM (mBOM)

> How the manufacturing BOM defines the planned structure of a build, including line items, quantities, alternates, and how runs consume it.

The mBOM is a part's planned parts list. See [Bills of materials overview](/build-hardware/bills-of-materials) for how it relates to the aBOM and build requirements. This page covers building and consuming it.

## mBOM line items

The mBOM table shows these columns per build requirement line:

| Column                    | Notes                                                                                                                                       |
| ------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------- |
| **Part Number / Rev**     | The required part, shown with its revision                                                                                                  |
| **Quantity**              | How many of the part go in. Multiplied by the parent's run quantity at execution time                                                       |
| **Substitutes**           | Approved alternate parts. See [Alternates and substitutes](/build-hardware/bills-of-materials/substitutes)                                  |
| **Reference Designators** | Positional identifiers such as `R12`, `U7`, and `Q1`. See [Reference designators](/build-hardware/bills-of-materials/reference-designators) |
| **Made on Assembly**      | Whether this part is built directly onto the parent. See [Made on assembly](/build-hardware/bills-of-materials/made-on-assembly)            |

For the GraphQL shape, see [mBOMs API](/api-reference/examples/mboms).

## Creating an mBOM

1. Open the parent **part** in the Parts Library.
2. Find the **mBOM** card on the part page. If the part has no mBOM yet, click **Create mBom**.
3. With the version in **Draft**, click **New Part** and pick the child part. ION adds a line with a quantity of 0.
4. For each line, set the **Quantity** and optionally add substitutes, reference designators, and the **Made on Assembly** checkbox directly in the row.

Edits save as you make them; there's no separate save step. mBOM lines are editable only while the version is in **Draft**. For version states and the release flow, see [Manage BOM versions](/build-hardware/bills-of-materials/versions).

<Note>
  The mBOM card on the part page is a quick editor. For the full mBOM, including its complete version history, use the **Go to full mBom** link in the card header.
</Note>

## Related

* [Bills of materials overview](/build-hardware/bills-of-materials)
* [As-built BOM (aBOM)](/build-hardware/bills-of-materials/as-built-bom)
* [Edit build requirements](/build-hardware/bills-of-materials/editing-build-requirements)
* [Alternates and substitutes](/build-hardware/bills-of-materials/substitutes)
* [BOM versions and change management](/build-hardware/bills-of-materials/versions)
* [Parts](/build-hardware/parts)