A Configuration Baseline is the performance documentation and standards that comprise a product at a certain moment during its development. It is a set of documented specifications for a configuration item within a system that has been formally examined and agreed upon at a given time and can only be amended via change control procedures. Throughout the development lifecycle, the baseline is employed to measure, monitor, and manage changes.
Definition: A configuration baseline is a fixed reference in the development cycle or an agreed-upon specification of a product at a specific time which can only be changed through a change control process.
Purpose of Configuration Baselines
A configuration baseline aims to identify major changes and non-compliance to the performance of a configuration item throughout system development so that the program manager/Engineers can take appropriate action.
Types of Configuration Baselines
The Configuration Baseline is established for specific events in a program’s life cycle and contributes to the performance portion of a program’s Acquisition Program Baseline (APB). The overall Technical Baseline rolls up into the APB and consists of the following configuration baselines:
- Functional Baseline
- Allocated Baseline
- Product Baseline
Functional Baseline 
The functional baseline is the required system functionality describing functional and interface characteristics of the overall system and the verification required to demonstrate the achievement of those specified functional characteristics. This baseline is derived from the Capability Development Document (CDD) and normally includes a detailed functional performance specification for the overall system and the tests necessary to verify and validate overall system performance.
The functional baseline is normally established and put under configuration control at the System Functional Review (SFR). It is usually verified with a System Verification Review (SVR) and/or a Functional Configuration Audit (FCA).
Allocated Baseline 
The allocated baseline is the configuration items making up a system, and then how system function and performance requirements are allocated across lower-level configuration items (hence the term allocated baseline). It includes all functional and interface characteristics that are allocated from the top-level system or higher-level configuration items, derived requirements, interface requirements with other configuration items, design constraints, and the verification required to demonstrate the traceability and achievement of specified functional, performance, and interface characteristics. The performance of each configuration item in the allocated baseline is described in its preliminary design specification as are the tests necessary to verify and validate configuration item performance.
The allocated baseline is usually established and put under configuration control at each configuration item’s (hardware and software) Preliminary Design Review (PDR), culminating in a system-allocated baseline established at the system-level PDR.
Product Baseline 
The product baseline is the documentation describing all of the necessary functional and physical characteristics of a configuration item; the selected functional and physical characteristics designated for production acceptance testing; and tests necessary for deployment/installation, operation, support, training, and disposal of the configuration item. The initial product baseline includes “build-to” specifications for hardware (product, process, material specifications, engineering drawings, and other related data) and software (software module design— “code-to” specifications).
The Initial product baseline is usually established and put under configuration control at each configuration item’s Critical Design Review (CDR), culminating in an initial system product baseline established at the system-level CDR. By DoD policy, the PM shall assume control over this initial product baseline after the system-level CDR and control all Class 1 changes.
Until completion of the System Verification Review (SVR) and/or FCA, Class 1 changes shall be those changes that affect the government performance specification. Following the SVR/FCA, the government will further define contractually what constitutes a Class 1 change. The system product baseline is finalized and validated at the Physical Configuration Audit (PCA).
Configuration Management Information System
The DoD Configuration Management Information System (CMIS) supports the configuration, engineering, and technical data management functions of the Department of Defense (DoD) community with a standard Web-Based Automated Information System (AIS).
Another Type of Baseline: Technical Baseline
The Technical Baseline includes user requirements, program and product information, and related documentation for all configuration items (i.e., those system elements under configuration management). The technical baseline consists of the following Configuration Baselines: (Functional, Allocated, and Product)
|Major Documents in the Technical Baseline||Functional Baseline||Allocated Baseline||Product Baseline|
|System Performance Specifications||X|
|Item Performance Specifications||X|
|Item Details Specifications||X|
|External Interfaces Specifications / Interface Control Documents||X|
|Internal Interfaces Specifications / Interface Control Documents||X|
|Table: Baseline and Specifications|
AcqLinks and References:
-  Defense Acquisition Guidebook (DAG)
- MIL-HDBK-61A, “Configuration Management Guidance”
- MIL-STD-1916, “DOD Preferred Methods for Acceptance of Product”