And, from the Product Requirements Specification comes the…

PRODUCT DESIGN SPECIFICATION

This Specification describes how the product is to be designed to meet the Product Requirements Specification. This is the design, engineering, development and 'productizing' document that defines how the product is to be implemented. It includes the low-level functionality that will provide the product functionality defined in the Product Requirements Specification. This document is used for final Product Design Verification to prove that the product has been designed correctly. It includes:

• Selected technologies - Hardware and software components which will be used to provide the functionality at the cost desired.
• Detailed functionality & Interfaces - HW & SW Block diagrams, Flow charts, etc. which describe the implementation of the design.
• Regulatory/Safety Requirements needed to market the product in the targeted locations and meet corporate dictates.
• Mechanical Requirements needed to meet the functional, ergonomic and environmental requirements.
• Document Control Requirements needed to meet the desired or mandated Quality Processes.
• Environmental & Life requirements needed to meet the reliability and quality requirements and validate the warranty goals.
• Manufacturing/Service/QA - detailed test and metric requirements that need to be designed into and in support of the product.
• Engineering & Design Verification Test (EVT, DVT) methodologies required to verify that the selected technologies meet the cost and functionality requirements (EVT); and that the overall functionality and performance meet the entire specification (DVT): i.e. Is the product designed correctly?

This document sometimes is broken into two documents: (1) Product Hardware Design Specification and (2) Product Software Design Specification.

Also, from the Product Requirements Specification comes the…

PRODUCTION DESIGN SPECIFICATION

This Specification describes how the product is to be manufactured and maintained. It details the production and service processes as defined in the Product Requirements Specification. This document is used for final Production Verification Test to prove that the production process has been designed correctly. It includes:

• Production Processes required specific to the product.
• Document Control.
• QA, QC, ISO, EC etc. requirements and how to meet and maintain them.
• Detailed Manufacturing tests and methodologies.
• Detailed QA/AC methodologies needed to define ALL of the measurable Quality parameters, which will be tested.
• Supplier QA/QC requirements.
• Shipping methodologies and plans.
• Returned Material/Repair methodologies required to provide the appropriate level of testing needed for field service debug/go-nogo, factory service debug/go-nogo and what levels of product testing are needed to determine fix/throw-away decisions.
• Production Verification Test (PVT) methodologies required to verify that the overall production processes is designed correctly to provide the costs and quality of product stated in the Product Requirements Specification, and that the process is debugged and defect free. Manufacturing processes are defined, designed and require testing and debugging, just like any new product.

Some companies use more documents than these, but I believe these five basically outline and 'make manageable' a product development project.

The specifications described above require a mechanism that will ultimately be used to verify that what has been implemented was done correctly. Test plans are this mechanism.