DRAFT — under teacher review.
Essential Terms — C02
The Hamilton and Alexandra College · Year 12 · 2026
A glossary of every term you need to recognise and use correctly across C02. Click a term to expand its definition. Use this as a vocabulary self-check before your C2-1 (Poster Peer-Assessment) and C2-2 (Hand-Drawn Diagrams) validations — if you can't define a term in your own words, you can't defend it under questioning.
flowchart TD
R["C02 vocabulary<br/>26 terms"]
R --> G0["Data collection<br/>9 terms"]
R --> G1["Context diagrams and DFDs<br/>7 terms"]
R --> G2["Use case diagrams (UML)<br/>10 terms"]
Where the C02 vocabulary sits, and how much of it is in each group — the 3 sections below follow the same order. Revise the heavy groups first.
Data collection
Close-ended questions
Questions that can be answered with a finite set of responses
Data
Raw, unprocessed facts and figures
Interview
A face-to-face meeting between people for consultative purposes
Observation
A method of data collection that involves physically observing how a system operates and how it is used
Open-ended questions
Questions where the number of potential answers is infinite
Qualitative data
Data that consists of descriptive details, usually gathered via surveys or interviews
Quantitative data
Data that can be easily processed in a statistical manner, usually composed of definite numbers
Report
A written document providing a summary or finding in relation to the context or system being analysed
Survey
A set of questions that ask for a response to be selected from a list of alternatives
Context diagrams and DFDs
Context diagram
A visualisation of a system in its entirety that indicates the data that is passed into and out of the system
Data flow
The movement of a piece or collection of data within an information system, as shown in context diagrams and data flow diagrams (DFDs)
Data flow diagram (DFD)
A graphical visualisation of the flow of information within a system, including data provided by external entities
Data store
A representation of a collection of data that is stored in some way within a system
Entity
The users or external systems that interact with the system being created
Process (context diagram)
An abstract representation of the whole system being created
Process (data flow diagram)
An abstract representation of a function within a system
Use case diagrams (UML)
Actor
An entity that can interact with the software solution as shown in a use case diagram
Association
A relationship between two elements in a use case diagram
Extend
A relationship between use cases where one use case has optional or additional functionality, which is represented in a use case diagram as a second use case
Generalisation
A parent-child relationship between two elements in a use case diagram
Include
A relationship between use cases where one use case is tied to, or relies upon, the functionality contained within another use case
Relationship
The connections between elements within a use case diagram
System boundary
A rectangle around relevant use cases that indicates the use cases that are within the scope of the solution
Unified Modeling Language (UML)
A general-purpose visual modelling language
Use case
A representation of the transactions or functions a user (actor) can complete in a system, as shown in a use case diagram
Use case diagram (UCD)
A method of describing how a user interacts with a system, using Unified Modeling Language (UML)
See also
- C02 home page — everything else for this criterion
- Context Diagram — the highest-level view of your system
- Context Diagram vs Data Flow Diagram — what changes between Level 0 and Level 1
- What Is an Entity — entities aren't only people
- Excalidraw Diagram Starters — pre-framed canvases for rehearsing all three diagrams