> For the complete documentation index, see [llms.txt](https://docs.diracinc.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.diracinc.com/user-guide/project-open/using-model-based-definition.md).

# Using Model-Based Definition

This will cover how to configure and use model-based definition in your instructions.

Model-based definition (MBD) connects your CAD geometry to structured metadata like part numbers, names, revisions, and materials. Metadata is automatically extracted from your CAD models when they are uploaded.

## Configuring metadata associations

Metadata associations define which CAD metadata fields map to BuildOS fields. These are configured at the team level by an administrator.

1. Navigate to **Settings** → **Team**.
2. Scroll to the **Model-Based Definition Mappings** section.
3. The following shows each BuildOS field and its mapped sources:

<figure><img src="https://2740836029-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FuT4VlrqtSgrz4OSV9Xp4%2Fuploads%2FBvWPCaPxKcmGikPAfn2H%2FScreenshot%202026-02-24%20at%204.30.08%E2%80%AFPM.png?alt=media&amp;token=93340f5b-1997-4e81-bd19-3723c0adfa81" alt=""><figcaption></figcaption></figure>

### Adding a source

1. Click **Add source +** on the field you want to map.
2. Type the CAD metadata field name (e.g., "PART\_NAME", "ITEM\_NUM").
3. Click the **check icon** to save.

You can map up to 5 sources per field.

### Reordering source priority

Use the **left and right arrow buttons** on a source badge to change its priority. Sources are checked from left to right — BuildOS uses the first source that has data available.

### Removing a source

Click the **X icon** on a source badge to remove it.

## Viewing metadata in the model tree

You can display metadata values directly in the model tree labels.

1. Open the **Tree Options** menu above the model tree.
2. Under **Geometry Metadata**, select **Item Name** or **Item Number**.

The tree labels update to show the selected metadata field alongside the node name.

## Viewing metadata in the rename dialog

When you rename a node, the rename dialog shows metadata pulled from your CAD model.

1. Right-click a node and select **Rename**, or press **F2**.
2. The dialog shows read-only fields for:
   * **Item name** — from your CAD metadata
   * **Item number** — from your CAD metadata

You can insert metadata values into custom instruction names using formulas:

* `$iname` — Insert the item name
* `$inum` — Insert the item number

{% hint style="info" %}
If no metadata is found for a field, it displays "Not found". When multiple nodes with different metadata are selected, fields show "Multiple selected".
{% endhint %}

See the [concepts page for model-based definition](/how-to-be-successful-in-buildos/concepts/model-based-definition.md) to understand more!