Skip to content

Language Overview

Experience Notation is a plain-text, structured language for modelling human experiences across systems, services and scenarios. It is designed to be both human-friendly and machine-parseable, offering a formal yet flexible way to define events, actions, personas, and contextual dynamics.

Purpose

The language is built to:

  • Capture the complexity of human experience in a consistent format
  • Support simulation, analysis, testing, and design
  • Enable collaboration across disciplines (UX, AI, policy, research)

Experience Notation bridges the gap between unstructured user stories and fully automated simulation or verification frameworks.

Syntax Style

Experience Notation uses indentation-based, declarative syntax. It is designed to resemble readable outline-style prose:

Event: Login Attempt
  Step: Enter password
    User: Returning User
    Action: Types incorrect password
    UI-Element: Login form
    Conditional:
      IF: Password incorrect
      THEN: Show error
      ELSE: Proceed to dashboard

The syntax follows rules defined in an EBNF grammar.

File Header

Each .expn file starts with a required header block:

EBNF-Version: 1.1
Syntax-Version: 1.0
Journey-Title: Multi-Agent Access Control
Journey-Description: Interaction flow involving multiple user roles

These fields define which syntax and grammar version is used and provide a description of the journey being modelled.

Hierarchy and Structure

The language is structured hierarchically:

  • A journey contains one or more Events
  • Each Event contains one or more Steps, optionally Personas, Disruptions, Parallel Events, etc.
  • Each Step contains properties like User, Action, UI-Element, and optionally Conditional, Metrics, and Tags
Event: Checkout
  Step: Add Item to Basket
    User: Shopper
    Action: Clicks add button
    UI-Element: Product Page

Extensibility

Experience Notation allows:

  • Inline and external Persona definitions
  • Metadata via Meta: and Tag:
  • Conditional branches (IF, THEN, ELSE)
  • Cross-references via Ref: and ID:
  • Support for context modelling (Environmental-Factors, Disruption, Parallel-Events)

Validity and Compatibility

Experience Notation files are valid when:

Tools and validators (in progress) will allow automated checking and transformation of .expn files.

Continue to EBNF Grammar to see the formal structure.