Strategy Bridge

Systems Engineering Glossary

Term Main definition

A lower level entity derived from a higher level entity during the architecting process.

N2 Diagram

A matrix or similar graphical representation that identifies and defines the interface relationships between entities.

Operational Acceptance

The formal transfer of system responsibility from the acquirer to the Operations and Maintenance Manager of the end user.

Operational Concept (OPCON)

A clear and concise description of how a system will function in practice.

Operational Readiness Review

A review where all system and support hardware, software, personnel, procedures, and user documentation are examined to determine whether to proceed with an operational demonstration that verifies that the system will function according to specifications in the operational environment.

Operations and Maintenance (O&M)

A phase in the project life cycle after delivery that entails system operation, training, repairs and updates, and other items to ensure the system operates smoothly and efficiently.


The selection of the alternative the best satisfies all stakeholder needs and constraints based on defined evaluation criteria.


The lowest level of separately identifiable items that cannot be disassembled without destruction or impairment.

Peer Review

An independent evaluation of project deliverables by those with appropriate skills who are not responsible for the effort.


A quantitative measure of physical or functional attribute’s response during the exercise of a process, function, activity, or task.

Performance Index

The measure of effectiveness for each alternative.

Performance Requirement

A description of how well a product or system satisfies a need without regard to how it is accomplished.

Physical Configuration Audit (PCA)

A physical examination of a project’s artifacts to verify that the “as built” Configuration Items conform to the “build to “ documentation that defines them.

Precedence Diagram

A workflow diagram that depicts activity sequences with all predecessor and successor activities.

Preliminary Design

A process to define and architect system performance, components, interfaces, and data to the allocated requirements level.

Preliminary Design Review (PDR)

A review to approve the architecture, decomposition and allocation of requirements, models, and design concepts against system requirements.  The detailed design phase is entered once the preliminary design is approved.  (Typically referred to as the “Design-to-Base-line.”)


Actions that must complete prior to starting an event or progressing to the next phase or activity.

Preventative Maintenance

Actions performed on a regular basis to lesson the likelihood of a system component failure.


Any anomaly determined not to be a failure, but significant enough to warrant recording.


A series of steps or actions to transform inputs into outputs.