## š 1. UHT ā Identity of the Basic Light Switch
The light switch is a man-made, perceptible device that interacts with humans and changes its state based on user input.
### UHT Traits
```yaml
- 2: Man-made
- 6: Perceptible
- 13: Interacts with humans directly
````
### UHT Code
```text
UHT: 42 90 00 00
```
---
## š 2. UHR ā Semantic Relationships
The light switch:
- Receives user input to toggle its state
- Controls the power supply to a light bulb
### UHR Links
```yaml
- from: User
to: Light Switch
uhr: "C1" # Feeds ā
- from: Light Switch
to: Light Bulb
uhr: "C1" # Feeds ā
```
---
## ā±ļø 3. UHS ā Behavior Over Time
### States:
```yaml
- Idle: 42900000 # Passive, structural
- On: 42DA3000 # Active, light on
- Off: 42D02000 # Active, light off
```
### Transitions:
```yaml
- Idle ā On
trigger: Toggle ON
via: C1
- On ā Off
trigger: Toggle OFF
via: C1
- Off ā Idle
trigger: Reset
via: 81
```
---
## šØ 4. SDR ā Self-Describing Requirement
```yaml
id: SDR-LIGHTSWITCH-01
name: "Basic Light Switch"
description: "A human-operated switch that controls the power state of a light bulb."
must_have_traits:
- 2 # Man-made
- 6 # Perceptible
- 13 # Interacts with humans
required_links:
- relation: "Feeds ā"
uhr: "C1"
target_must_have: [10] # Light bulb must emit light
states:
- Idle
- On
- Off
delta_expected:
- from: Idle
to: On
add: [10] # Must emit light when on
```