Glossary
Core Terms
System - The main thing you're analyzing (large circle in BERT)
Subsystem - A component inside your system (smaller circles inside the system)
Boundary - The edge between your system and its environment (gray ring around system)
Environment - Everything outside your system that interacts with it
Interface - Connection point where your system meets the environment (rectangles on boundary)
Flows and Connections
Flow - Transfer of material, energy, or information between elements (arrow lines)
Source - External entity that provides inputs to your system (square outside system)
Sink - External entity that receives outputs from your system (square outside system)
Resource - Useful input your system needs to function
Product - Primary valuable output your system creates
Waste - Byproducts or unusable outputs from your system
Flow Types
Material - Physical substances (food, parts, documents)
Energy - Power, heat, or work (electricity, fuel, labor)
Information - Data, signals, or messages (orders, feedback, instructions)
System Properties
Complexity - How your system behaves:
Simple: Predictable, fixed behavior
Adaptive: Responds to environmental changes
Evolvable: Can restructure itself permanently
Equivalence - Component type classification (what kind of thing it is)
Protocol - Rules governing how an interface operates
Porosity - How open a boundary is to flows passing through
Analysis Concepts
Decomposition - Breaking a system into subsystems for deeper analysis
Recursive Analysis - Treating any subsystem as a new system to analyze
Transformation - How a system converts inputs into outputs
Model - Your BERT diagram representing the system
Practical Examples
System
Restaurant
Subsystem
Kitchen
Interface
Order counter
Source
Food supplier
Sink
Customer
Product flow
Prepared meals
Waste flow
Food scraps
Resource flow
Raw ingredients
Need more detail? See the 11-step tutorial for hands-on practice with these concepts.
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