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

# Units and frames

> SI units, unit-suffixed field names, and the frame tree.

* All physical quantities use **SI units**. Field names carry unit suffixes: `_m`, `_rad`, `_s`, `_ns`, `_mps`, `_radps`, `_n` (newtons), `_nm` (newton-metres), `_kg`, `_hz`. `[AWP-UNI-001]`
* Coordinate systems are **right-handed**; rotations are unit quaternions `q: [x, y, z, w]`. `[AWP-UNI-002]`
* The world publishes a **frame tree** in `session.ready`: named frames with parent links and static or timestamped transforms. Every pose in any message MUST name its frame; the frame MUST exist in the tree. `[AWP-UNI-003]`
* Dynamic transforms (e.g. `base` → `world` for a mobile robot) are published on the reserved `awp.tf` channel. `[AWP-UNI-004]`

```json awp:frame-tree theme={null}
{ "frames": [
  { "id": "world", "parent": null },
  { "id": "base",  "parent": "world", "dynamic": true },
  { "id": "cam_wrist", "parent": "arm_01_ee",
    "transform": { "p_m": [0,0,0.05], "q": [0,0,0,1] } }
]}
```