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Accessibility Specification

a2p includes standardized accessibility preferences for adaptive UI.

Overview

Accessibility preferences enable services to automatically adapt interfaces for users with disabilities. Part of a2p:preferences.accessibility.

Categories

Category Description
Vision Screen reader, magnification, color blindness
Hearing Captions, visual alerts, sign language
Motor Keyboard-only, voice control, switch access
Cognitive Simplified UI, reading assistance
Sensory Reduce flashing, quiet mode
Physical Wheelchair, allergies, dietary, service animal

Vision Preferences

{
  "vision": {
    "screenReader": true,
    "magnification": 1.5,
    "highContrast": "high",
    "colorVision": {
      "type": "deuteranopia",
      "severity": "moderate"
    },
    "prefersDarkMode": true,
    "fontSize": "large",
    "reducedMotion": true
  }
}

Color Vision Types

Type Description UI Adaptation
protanopia Red-blind Avoid red/green
deuteranopia Green-blind Avoid red/green
tritanopia Blue-blind Avoid blue/yellow
achromatopsia Color blind Use patterns

Hearing Preferences

{
  "hearing": {
    "deaf": true,
    "captions": {
      "enabled": true,
      "style": "large"
    },
    "signLanguage": "ASL",
    "prefersVisualAlerts": true
  }
}

Motor Preferences

{
  "motor": {
    "keyboardOnly": true,
    "reducedMotion": true,
    "largeClickTargets": true,
    "extendedTimeouts": true
  }
}

Cognitive Preferences

{
  "cognitive": {
    "simplifiedUI": true,
    "readingAssistance": {
      "dyslexiaFont": true,
      "lineSpacing": "wide"
    },
    "plainLanguage": true
  }
}

Generative UI Integration

Services with generative UI can adapt automatically:

  1. Request a2p:preferences.accessibility
  2. Receive user preferences
  3. Generate adapted interface
  4. Result: Personalized accessible UI

Physical Accessibility

For real-world services (restaurants, hotels, travel, hospitals):

{
  "physical": {
    "mobility": {
      "wheelchair": true,
      "wheelchairType": "electric",
      "requiresAccessibleEntrance": true
    },
    "serviceAnimal": {
      "has": true,
      "type": "guide_dog",
      "name": "Max"
    },
    "allergies": {
      "food": ["peanuts", "shellfish"],
      "severity": { "peanuts": "anaphylactic" },
      "epiPenCarrier": true
    },
    "dietary": {
      "restrictions": ["vegetarian", "halal"],
      "intolerances": ["lactose"]
    },
    "specialAssistance": {
      "earlyBoarding": true,
      "preferredSeating": "aisle"
    }
  }
}

Use Cases

Service Uses
Restaurant Allergies, dietary
Hotel Wheelchair room, service animal
Airline Early boarding, seating, dietary
Hospital All medical info, allergies

Standards Alignment

  • WCAG 2.2 — Web Content Accessibility Guidelines
  • WAI-ARIA — Accessible Rich Internet Applications
  • EN 301 549 — European accessibility standard
  • ADA — Americans with Disabilities Act

Next Steps