Functional design documents help developers, testers, and customers to understand the customizations in detail. The following are key benefits of FDDs:

• FDDs help the development team to understand the feature and provide a clear scope and definition of what to develop. Function design documents streamline the development process. The development team working on the feature has a clear understanding and answers to all their functionality-related questions to start development. Since this document is approved by the customer, the developers only develop customizations/extensions that are authorized.
• FDDs help the testing team to understand the feature under development and to develop a test plan around it.
• FDDs provide the customer with a clear vision and definition of the feature being developed. Also, it helps the entire project team to visualize and see the solution long before it is built.
• FDDs provide the baseline of the training documentation for the application support team and business users.

Now let's understand important pointers for a project manager in the design phase of the implementation project.