Story of concrete user–system interaction used to capture behaviour.
Scenario
Set of scenarios tied to a user goal; often lists main and alternative flows.
Use Case
Requirement stating what user and computer accomplish together; postpones who does what.
Task Description
Extension of a task that lists current problems and proposed computer support for each subtask/variant.
Tasks & Support
Four abstraction levels: Goal → Domain → Product → Design.
Goal–Design Scale
Conceptual map of real-world entities and relationships (not a database schema).
Domain Model
Create, Read, Update, Delete operations over data.
CRUD
Checking we built the product right (meets its specification).
Verification
Checking we built the right product (meets user needs).
Validation
Task element indicating how often and how intense the task demand is; surfaces quality hotspots.
Frequency/Criticality
Alternative condition/path within a task (e.g., booked vs walk-in).
Variant
End-to-end process showing actors, dependencies, sequencing.
Workflow
Requirement type describing behaviour transformations from inputs/state to outputs/state.
Functional Requirement
Requirement type specifying what must be stored/exchanged; formats and persistent state.
Data Requirement
Requirement type specifying how well the system performs (e.g., performance, usability).
Quality Requirement
Choosing levels appropriate to the supplier: vendor vs software house vs consultancy.
Selecting Requirement Level
Common trap: specifying UI fields and database columns while modelling the domain.
Solution Bias in Domain Modelling
Good task property: clear closure—user feels ‘done’.
Closed Task
Method to validate requirements by simulating tasks and all variants with users.
Task-based Validation
Linking business goals to specific tasks ensures traceability and correct focus.
Tracing Goals to Tasks
Why postpone the human/computer split in requirements? To keep design space open and avoid premature constraints.
Rationale for Postponing Split
Example of Task & Support improvement for hotel keys.
Electronic Keys Support
Guest’s ‘Hotel Stay’ adds tasks like Select Hotel and Reimburse—revealing missing requirements.
Client-Perspective High-Level Task
How tasks surface quality needs: frequency/critical scenarios indicate performance/usability targets.
Tasks as Quality Pointers
