Strategy Bridge

Systems Engineering Glossary

Term Main definition

The relationships among milestones and/ or activities that affect other milestones.


The characteristics that are required to form the boundary between entities.

Interface Controlled Document (ICD)

A controlled specification that describes the physical, functional, logical, and electrical characteristics that an entity uses to communicate with its environment.

Interface Requirement

A statement of the functional, physical, logical, and electrical constraints that exist between multiple entities that describe how they fit together.


The ability of a system or its parts to exchange services or data with other systems.

Key Decision Point (KDP)

A milestone where readiness of a project/ program to move to the next phase of the life cycle is determined.

Key Performance Parameters (KPPs)

The minimum number of attributes or characteristics that are considered essential for an effective capability.


An existing system that must be taken into account when developing a new system.

Lessons Learned

A technique to utilize past experience, especially failures, to improve future performance.


Documentation of an unsatisfied requirement or task that must be completed within a designated timeframe in order to transition to the next step or phase in the life cycle.

Life Cycle

A conceptual model that describes the stages of activity involved in developing a project.

Life Cycle Cost (LCC)

The total cost to the organization of acquisition and ownership of a system over its life.  It includes all costs associated with the system and its use from concept to disposal.

Life Cycle Model

A framework depicting the phases of processes and activities necessary for system implementation.


The ability, ease, and swiftness to restore a system to functionality after a failure or defect.


The allowances carried in budget, projected schedules, and technical performance parameters (e.g., weight, power, or memory) to account for risk.

Measure of Effectiveness (MOE)

A measure that indicates how well a system achieves intended operational capabilities in its intended environment.

Measures of Performance (MOP)

Quantifiable measures of how well a system is expected to satisfy defined parameters in its operational environment.


A specific definable accomplishment at a given point in time where approval is sought to start or continue into the next phase of the program.


A representation of a real-world process, concept, or system that uses logical expressions to predict how a system might perform under different conditions.

Model-Based Systems Engineering

Formal utilization of models to support all technical Systems Engineering (SE) activities throughout the life cycle phases.