KNOWLEDGE BASE // GLOSSARY

MBSE Glossary

Key terms and language of model-based practice — the vocabulary you'll use in every SET Academy course and on every digital engineering program.

28 TERMS

MBSE

Model-Based Systems Engineering — the formalized application of modeling to support system requirements, design, analysis, verification, and validation across the entire lifecycle.

SysML

The Systems Modeling Language — a graphical modeling language standardized by the OMG for specifying, analyzing, designing, and verifying complex systems.

Model

A digital, structured representation of a system that serves as the authoritative source of engineering truth — replacing scattered documents and spreadsheets.

Digital Engineering

An integrated, digital approach that uses authoritative sources of system data and models across the lifecycle — the umbrella practice that MBSE lives within.

Digital Thread

The connected flow of data linking requirements, design models, analysis, manufacturing, and sustainment — so every discipline works from the same information.

Digital Twin

A virtual representation of a physical system, kept in sync with its real-world counterpart to support simulation, prediction, and operations.

Requirement

A condition or capability a system must satisfy. In MBSE, requirements live in the model and are traced directly to the design elements that satisfy them.

System Architecture

The structure of a system — its components, their relationships, and the principles governing its design and evolution — captured as model elements.

Block

The fundamental structural unit in SysML, used to represent systems, subsystems, components, and their properties and interfaces.

Use Case

A description of how actors (users or external systems) interact with the system to achieve a goal — a primary tool for capturing functional behavior.

Trade Study

A structured comparison of design alternatives against weighted criteria, performed in or alongside the model to drive objective design decisions.

Verification & Validation

Verification confirms the system is built right (meets requirements); validation confirms the right system was built (meets the need). MBSE traces both through the model.

Parametric Analysis

Using SysML parametric diagrams to bind system properties to engineering equations — enabling analysis and simulation directly from the model.

DoDI 5000.97

The Department of Defense instruction mandating digital engineering — including MBSE — across defense acquisition programs.

Stakeholder

Any individual or organization with an interest in the system — customers, operators, regulators — whose needs the model must capture and satisfy.

Systems Engineering

The interdisciplinary practice of designing, integrating, and managing complex systems over their lifecycles — balancing performance, cost, schedule, and risk.

Systems Thinking

Viewing a system as a whole — its parts, interactions, and environment — rather than as isolated components. The foundational mindset of every SET Academy course.

Lifecycle

The full span of a system's existence — from concept and design through production, operation, sustainment, and retirement — all traceable within the model.

Interface

A defined boundary where two system elements exchange energy, data, or material. Modeling interfaces early is one of MBSE's biggest defect-prevention wins.

Traceability

The ability to follow a requirement from stakeholder need to design element to verification result — a core property of a well-built system model.

Actor

A person or external system that interacts with the system of interest — represented in use case diagrams to define the system boundary.

State Machine

A behavioral model describing the states a system can be in and the events that trigger transitions between them.

Stereotype

A SysML extension mechanism that tailors a model element for a specific domain — letting teams adapt the language to their program's vocabulary.

Model Repository

The managed storage where system models live — providing version control, access control, and collaboration for distributed engineering teams.

Authoritative Source of Truth

The single, governed location — the model — where the current, approved definition of the system resides, ending conflicts between duplicated documents.

OMG

The Object Management Group — the standards consortium that maintains SysML, UML, and related modeling standards.

Capstone

The culminating SET Academy course — a full end-to-end MBSE project modeled on real aerospace and defense mission problems.

Simulation

Executing a model to predict system behavior before anything is built — validating designs early, when changes are cheapest.