# draw.io XML Reference
Detailed reference for styles, edge routing, containers, layers, tags, metadata, and dark mode. Consult this when generating draw.io XML diagrams.
## General principles
- **Use proper draw.io shapes and connectors** — choose the semantically correct shape for each element (e.g., `shape=cylinder3` for databases and tanks, `rhombus` for decisions, `shape=mxgraph.pid2valves.*` for valves in P&IDs). draw.io has extensive shape libraries; prefer domain-appropriate shapes over generic rectangles.
- **Decide whether to search for shapes** — before generating a diagram, decide if it needs domain-specific shapes from draw.io's extended libraries. **Skip `search_shapes`** for standard diagram types that use basic geometric shapes: flowcharts, UML (class, sequence, state, activity), ERD, org charts, mind maps, Venn diagrams, timelines, wireframes, and any diagram using only rectangles, diamonds, circles, cylinders, and arrows. Also skip if the user explicitly asks to use basic/simple shapes or says not to search. **Use `search_shapes`** when the diagram requires industry-specific or branded icons: cloud architecture (AWS, Azure, GCP), network topology (Cisco, rack equipment), P&ID (valves, instruments, vessels), electrical/circuit diagrams, Kubernetes, BPMN with specific task types, or any domain where the user expects realistic/standardized symbols rather than labeled boxes.
- **Match the language of labels to the user's language** — if the user writes in German, French, Japanese, etc., all diagram labels, titles, and annotations should be in that same language.
## Common styles
**Rounded rectangle:**
```xml
```
**Diamond (decision):**
```xml
```
**Arrow (edge):**
```xml
```
**Labeled arrow:**
```xml
```
## Style properties
| Property | Values | Use for |
|----------|--------|---------|
| `rounded=1` | 0 or 1 | Rounded corners |
| `whiteSpace=wrap` | wrap | Text wrapping |
| `fillColor=#dae8fc` | Hex color | Background color |
| `strokeColor=#6c8ebf` | Hex color | Border color |
| `fontColor=#333333` | Hex color | Text color |
| `shape=cylinder3` | shape name | Database cylinders |
| `shape=mxgraph.flowchart.document` | shape name | Document shapes |
| `ellipse` | style keyword | Circles/ovals |
| `rhombus` | style keyword | Diamonds |
| `edgeStyle=orthogonalEdgeStyle` | style keyword | Right-angle connectors |
| `edgeStyle=elbowEdgeStyle` | style keyword | Elbow connectors |
| `dashed=1` | 0 or 1 | Dashed lines |
| `swimlane` | style keyword | Swimlane containers |
| `group` | style keyword | Invisible container (pointerEvents=0) |
| `container=1` | 0 or 1 | Enable container behavior on any shape |
| `pointerEvents=0` | 0 or 1 | Prevent container from capturing child connections |
## Edge routing
**CRITICAL: Every edge `mxCell` must contain a `` child element**, even when there are no waypoints. Self-closing edge cells (e.g. ``) are invalid and will not render correctly. Always use the expanded form:
```xml
```
draw.io does **not** have built-in collision detection for edges. Plan layout and routing carefully:
- Use `edgeStyle=orthogonalEdgeStyle` for right-angle connectors (most common)
- **Space nodes generously** — at least 60px apart, prefer 200px horizontal / 120px vertical gaps
- Use `exitX`/`exitY` and `entryX`/`entryY` (values 0-1) to control which side of a node an edge connects to. Spread connections across different sides to prevent overlap
- **Leave room for arrowheads**: The final straight segment of an edge (between the last bend and the target shape, or between the source shape and the first bend) must be long enough to fit the arrowhead. The default arrow size is 6px (configurable via `startSize`/`endSize` styles). If the final segment is too short, the arrowhead overlaps the bend and looks broken. Ensure at least 20px of straight segment before the target and after the source when placing waypoints or positioning nodes
- When using `orthogonalEdgeStyle`, the auto-router places bends automatically — if source and target are close together or nearly aligned on one axis, the router may place a bend very close to a shape, leaving no room for the arrow. Fix this by either increasing node spacing or adding explicit waypoints that keep the final segment long enough
- Add explicit **waypoints** when edges would overlap:
```xml
```
- Use `rounded=1` on edges for cleaner bends
- Use `jettySize=auto` for better port spacing on orthogonal edges
- Align all nodes to a grid (multiples of 10)
- **Edge labels**: Do NOT wrap edge labels in HTML markup to reduce font size. The default font size for edge labels is already 11px (vs 12px for vertices), so they are already smaller. Just set the `value` attribute directly.
## Containers and groups
For architecture diagrams or any diagram with nested elements, use draw.io's proper parent-child containment — do **not** just place shapes on top of larger shapes.
### How containment works
Set `parent="containerId"` on child cells. Children use **relative coordinates** within the container.
### Container types
| Type | Style | When to use |
|------|-------|-------------|
| **Group** (invisible) | `group;` | No visual border needed, container has no connections. Includes `pointerEvents=0` so child connections are not captured |
| **Swimlane** (titled) | `swimlane;startSize=30;` | Container needs a visible title bar/header, or the container itself has connections |
| **Custom container** | Add `container=1;pointerEvents=0;` to any shape style | Any shape acting as a container without its own connections |
### Key rules
- **Always add `pointerEvents=0;`** to container styles that should not capture connections being rewired between children
- Only omit `pointerEvents=0` when the container itself needs to be connectable — in that case, use `swimlane` style which handles this correctly (the client area is transparent for mouse events while the header remains connectable)
- Children must set `parent="containerId"` and use coordinates **relative to the container**
### Example: Architecture container with swimlane
```xml
```
### Example: Invisible group container
```xml
```
## Layers
Layers control visibility and z-order. Every cell belongs to exactly one layer. Use layers to manage diagram complexity — viewers can toggle layer visibility to show or hide groups of elements (e.g., "Physical Infrastructure" vs "Logical Network" vs "Security Zones").
Cell `id="0"` is the root and cell `id="1"` is the default layer — both always exist. Additional layers are `mxCell` elements with `parent="0"`:
```xml
```
- A layer is an `mxCell` with `parent="0"` and no `vertex` or `edge` attribute
- Assign shapes to a layer by setting `parent` to the layer's id
- Later layers render on top of earlier layers (higher z-order)
- Add `visible="0"` as an attribute on the layer cell to hide it by default
- Use layers when the diagram has distinct conceptual groupings that viewers may want to toggle independently
## Tags
Tags are visual filters that let viewers show or hide elements by category. Unlike layers, a single element can have multiple tags, making tags ideal for cross-cutting concerns (e.g., tagging shapes as "critical", "v2", or "backend").
Tags require wrapping `mxCell` in an `