> ## 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.

# BIM data patterns

> How connector-published BIM data is structured in Speckle Object Model v3 — DataObject, properties, and proxies

## Goal

Understand how walls, doors, rooms, and other BIM elements appear in SpeckleSharp so you can filter, extract, and report on connector-published data.

## What you will learn

How v3 stores BIM semantics in `DataObject.properties`, why there are no typed `Wall` classes, and where proxies fit in.

## When to use this

Read this before writing filters or CSV exports on data from **Revit, Rhino, ArchiCAD**, or other connectors. If you only need a working script, start with [Build your first model analysis tool](/developers/sdks/dotnet/guides/build-your-first-model-analysis-tool) and return here when property names are unclear.

## Recommended approach

1. Receive with `Receive2`
2. Treat elements as **`DataObject`** — check **`properties`**, not `speckle_type`, for BIM meaning
3. Use `Flatten()` for model-wide queries
4. Resolve **proxies** when you need levels, groups, or instances — see [Working with Proxies](/developers/sdks/dotnet/guides/working-with-proxies)

## Complete example

```csharp Complete example lines icon="https://mintcdn.com/speckle/VtRPWzmN-ULoLfIv/images/developers/sdks/csharp.svg?fit=max&auto=format&n=VtRPWzmN-ULoLfIv&q=85&s=f2970e3b8bd4a2c7899b46211a42f251" expandable theme={null}
using Speckle.Objects.Data;
using Speckle.Sdk.Models;
using Speckle.Sdk.Models.Extensions;

// After Receive2 — connector data is usually DataObject
var root = await SpeckleBootstrap.Operations.Receive2(/* ... */);

foreach (var obj in root.Flatten().OfType<DataObject>())
{
    Console.WriteLine(obj.name); // "Basic Wall - 200mm"
    Console.WriteLine(obj.speckle_type); // "Objects.Data.DataObject" — same for all BIM elements

    if (obj.properties.TryGetValue("category", out var cat))
        Console.WriteLine($"  category: {cat}");

    // Nested Revit-style parameters
    if (obj.properties["parameters"] is Dictionary<string, object?> paramGroups)
    {
        foreach (var (groupName, group) in paramGroups)
            Console.WriteLine($"  parameter group: {groupName}");
    }
}

// Good — filter by properties
var walls = root.Flatten()
    .OfType<DataObject>()
    .Where(d => d.properties.GetValueOrDefault("category")?.ToString() == "Walls");

// Avoid — speckle_type is not "Wall" or "Door" in v3
// if (obj.speckle_type.Contains("Wall")) { ... }
```

## How it works

### v3 object types

In Object Model v3, connectors emit generic containers:

| Type                                    | Role                                                  |
| --------------------------------------- | ----------------------------------------------------- |
| `DataObject`                            | BIM element with `name`, `properties`, `displayValue` |
| `Collection`                            | Hierarchy (building → level → category)               |
| Geometry (`Point`, `Mesh`, …)           | In `displayValue` or nested properties                |
| Proxies (`GroupProxy`, `LevelProxy`, …) | Organisation metadata at the root                     |

BIM semantics live in **`properties`** — category, family, type, level, fire rating, Revit parameters, and custom fields.

### Deep nesting

Properties can nest several levels:

```csharp Example lines icon="https://mintcdn.com/speckle/VtRPWzmN-ULoLfIv/images/developers/sdks/csharp.svg?fit=max&auto=format&n=VtRPWzmN-ULoLfIv&q=85&s=f2970e3b8bd4a2c7899b46211a42f251" theme={null}
// Direct property
obj.properties["volume"]

// Nested material data (shape varies by connector)
// obj.properties["materials"]["Steel"]["area"]
```

### No typed BIM classes

There is no `Wall` or `Column` class in SpeckleSharp for connector data. Use property checks:

```csharp Example lines icon="https://mintcdn.com/speckle/VtRPWzmN-ULoLfIv/images/developers/sdks/csharp.svg?fit=max&auto=format&n=VtRPWzmN-ULoLfIv&q=85&s=f2970e3b8bd4a2c7899b46211a42f251" theme={null}
if (obj.properties.GetValueOrDefault("category")?.ToString() == "Walls")
    Console.WriteLine($"Wall: {obj.name}");
```

### Proxies and hierarchy

Revit levels and groups often appear as **proxies** at the root, not as parent nodes in the tree. See [Working with Proxies](/developers/sdks/dotnet/guides/working-with-proxies) and [Find objects by property](/developers/sdks/dotnet/guides/finding-and-extracting-data).

## Common mistakes

| Mistake                                        | Fix                                               |
| ---------------------------------------------- | ------------------------------------------------- |
| Looking for `speckle_type == "Wall"`           | Filter `properties["category"]`                   |
| Expecting Revit parameter names in UI language | Inspect `properties` keys on a sample object      |
| Ignoring proxies for level-based reports       | Index by `applicationId` and resolve proxies      |
| Using `obj["category"]` on all objects         | Prefer `DataObject.properties` for connector data |

## Next steps

<CardGroup cols={3}>
  <Card title="Find objects by property" icon="magnifying-glass" href="/developers/sdks/dotnet/guides/finding-and-extracting-data">
    Traversal and filter recipes
  </Card>

  <Card title="Working with Proxies" icon="link" href="/developers/sdks/dotnet/guides/working-with-proxies">
    Levels, groups, and instances
  </Card>

  <Card title="Export model data to CSV" icon="file-csv" href="/developers/sdks/dotnet/guides/export-model-data-to-csv">
    Door and room schedules
  </Card>
</CardGroup>