> For the complete documentation index, see [llms.txt](https://docs.openbrim.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.openbrim.org/templates/cadd/level-cadd.md).

# Level (CAD Layer)

A **Level** is the CAD equivalent of a layer (in DWG/DXF terminology). Every shape, dimension, and annotation in a CAD document is assigned to a Level, and the Level controls how that shape is drawn — color, line weight, dash style. Routing styling through Levels rather than setting it shape-by-shape is what gives bridge drawings their conventional look (heavy dark lines for cut concrete, light gray for centerlines, dashed for hidden, red for hot work) without manually styling every shape.

Every CAD document has at least a "Default" level, created automatically. Add more for the conventions your sheets need: Centerlines, Hidden, Working, Concrete, Steel, Hardware, Bearings, Foundations, etc.

## Properties

**Name:** Identifier of the level. Used when assigning shapes to levels — set the shape's Level field to this name. Conventions: capitalize and avoid spaces (e.g., `Concrete`, `WorkingLines`).

**Color:** Color used for shapes assigned to this level. Hex (`#000000`) or RGB (`rgb(0, 0, 0)`) format. Black for cut lines on plotted sheets, red for hot work / revision callouts, gray (`#888888`) for projection and reference lines.

**Thickness:** Line weight in plot units. Heavy weights (3.0–4.0) for cut concrete on a section, medium (1.5) for projection, light (0.5–1.0) for centerlines and working lines.

**Line Style:** Dash pattern for the level. Choices include solid, dashed, dotted, dashdot, center, hidden, phantom. Match to drafting conventions: solid for visible cut and outline lines, hidden for occluded edges, center for centerlines.

## Typical level set

A practical starting set of levels for bridge drawings:

| Level          | Color     | Weight | Style  | Use                                  |
| -------------- | --------- | ------ | ------ | ------------------------------------ |
| **Default**    | Black     | 1.0    | Solid  | Catch-all for unassigned shapes.     |
| **Cut**        | Black     | 3.0    | Solid  | Heavy cut lines on sections.         |
| **Projection** | Dark gray | 1.5    | Solid  | Visible silhouette behind cut.       |
| **Hidden**     | Gray      | 1.0    | Hidden | Hidden / occluded silhouette.        |
| **Centerline** | Red       | 1.0    | Center | Centerlines, axis symbols.           |
| **Working**    | Gray      | 0.5    | Dashed | Construction working lines.          |
| **Concrete**   | Black     | 2.0    | Solid  | Cut concrete, hatched concrete fill. |
| **Steel**      | Black     | 2.0    | Solid  | Cut/visible steel members.           |
| **Bearings**   | Dark gray | 1.5    | Solid  | Bearing devices and pads.            |
| **Hardware**   | Dark gray | 1.0    | Solid  | Anchor bolts, dowels, connectors.    |
| **Dimension**  | Black     | 0.5    | Solid  | Dimension lines and text.            |
| **Notes**      | Black     | 0.7    | Solid  | Text annotations, leader lines.      |

## Notes

Levels are local to their CAD document — defining "Concrete" in one document doesn't automatically share it with another. For consistent conventions across many sheets, define levels in a shared project-level location and reference them.

Shapes always show with their level's color/weight/style unless the shape itself explicitly overrides those values. The override path exists for one-off shapes that need to look different from their level — but for production drawings the conventional approach is "shape gets a level, level dictates style."


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