What is the function of a CAD library?

The function of a CAD library is primarily to provide a directory of commonly used parts. This library contains standard components, symbols, and elements that designers can reutilize across different projects, enhancing efficiency and consistency in design. By having these commonly used parts readily accessible, designers can quickly incorporate them into new projects without the need to recreate these items from scratch. This not only saves time but also ensures that the designs comply with industry standards and best practices.

The other options, while they pertain to aspects of design or project management, do not capture the primary purpose of a CAD library. Storing completed designs refers more to project management or version control systems, managing project deadlines is related to project management tools, and creating new design elements from scratch falls under design tasks that happen outside the predefined elements stored in a library.