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

# AutoCAD Schema

> Data schema and structure for AutoCAD models

The AutoCAD connector exports geometry and objects from AutoCAD, preserving layer organization and extended data.

## Hierarchy

AutoCAD models are organized by File and Layer:

```mermaid theme={null}
graph TD
    A[Root Collection] --> B[AutoCAD File]
    A --> C[Proxies: RenderMaterial array]
    A --> D[Proxies: Color array]
    A --> E[Proxies: Group array]
    A --> F[Proxies: Definition array]
    
    B --> G[Layer]
    G --> H[Geometry<br/>standalone]
    G --> I[Instance]
```

The hierarchy reflects AutoCAD's layer structure:

* **File** - The AutoCAD file
* **Layer** - AutoCAD layer

## Object Types

AutoCAD exports three types of objects:

1. **Geometry** - Standalone geometry objects (Point, Line, Polyline, Arc, etc.)
2. **Instance** - Block references pointing to Definition proxies
3. **DataObject** - Objects with attached extended data (less common)

### Geometry Objects

Standalone geometry objects can appear directly in collections:

```json theme={null}
{
  "speckle_type": "Objects.Geometry.Line",
  "id": "...",
  "applicationId": "handle-123",
  "start": {"x": 0, "y": 0, "z": 0},
  "end": {"x": 10, "y": 10, "z": 0},
  "units": "meters"
}
```

### Instance Objects

Instance objects reference Definition proxies for block definitions:

```json theme={null}
{
  "speckle_type": "Objects.Instance",
  "applicationId": "instance-handle",
  "definitionId": "block-guid",
  "transform": {
    "speckle_type": "Objects.Geometry.Matrix",
    "value": [1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 10, 20, 30, 1]
  },
  "units": "meters"
}
```

## Properties

Geometry and Instance objects can have a `properties` field dynamically attached containing:

* **Extension Dictionaries** - Custom data stored in extension dictionaries
* **XData** - Extended entity data

```json theme={null}
{
  "speckle_type": "Objects.Geometry.Line",
  "applicationId": "handle-123",
  "start": {"x": 0, "y": 0, "z": 0},
  "end": {"x": 10, "y": 10, "z": 0},
  "properties": {
    "Extension Dictionaries": {
      "CustomApp": {
        "Key1": "Value1",
        "Key2": "Value2"
      }
    },
    "XData": {
      "AppName": "MyApp",
      "Data": [1001, "Tag", 1002, "Value"]
    }
  },
  "units": "meters"
}
```

## Proxies

AutoCAD models use these proxy types:

### RenderMaterial

Material assignments for visual representation.

### Color

Color assignments for objects. Referenced by objects via `applicationId`.

### Group

Group proxies encode AutoCAD group memberships. Objects can belong to multiple groups.

### Definition

Definition proxies store geometry for block definitions. Referenced by Instance objects via `definitionId`.

## Example: AutoCAD Geometry Object

```json theme={null}
{
  "id": "line-abc123...",
  "speckle_type": "Objects.Geometry.Line",
  "applicationId": "handle-456",
  "start": {"x": 0, "y": 0, "z": 0},
  "end": {"x": 10, "y": 10, "z": 0},
  "properties": {
    "Extension Dictionaries": {
      "MyApp": {
        "Layer": "A-WALL",
        "Type": "Structural"
      }
    }
  },
  "units": "meters"
}
```

## Example: AutoCAD Instance

```json theme={null}
{
  "id": "instance-xyz789...",
  "speckle_type": "Objects.Instance",
  "applicationId": "instance-handle-789",
  "definitionId": "block-door",
  "transform": {
    "speckle_type": "Objects.Geometry.Matrix",
    "value": [1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 5, 10, 0, 1]
  },
  "units": "meters"
}
```

## Invariants and Caveats

1. **Standalone geometry** - Geometry objects can exist directly in collections
2. **Instance/Definition pattern** - Block instances use the Instance/Definition proxy pattern
3. **Properties are optional** - Not all geometry objects have properties
4. **Layer organization** - Objects are organized by AutoCAD's layer structure
5. **Extended data in properties** - Extension dictionaries and XData appear in `properties` field
6. **No Info fields** - AutoCAD models don't include Info fields

<AccordionGroup>
  <Accordion title="How do I access block definition geometry?">
    Use the Instance's `definitionId` to find the corresponding Definition proxy, then access `proxy.value.displayValue` to get the geometry.
  </Accordion>
</AccordionGroup>

## Related Documentation

* [Object Schema](/developers/data-schema/object-schema) - Base object structure
* [Geometry Schema](/developers/data-schema/geometry-schema) - Geometry storage
* [Proxy Schema](/developers/data-schema/proxy-schema) - How proxies work