Where can you find an index to all sheets included in the plan set?

The key sheet serves as an essential part of the plan set by providing an index that lists all sheets included in the documents. It acts as a roadmap, allowing users to quickly locate specific drawings or details within the set. This ensures that anyone reviewing the plans can efficiently navigate through the various sheets and find necessary information without having to sift through each individual page.

The cover sheet typically contains general information about the project, including title, location, and company details, but does not provide a comprehensive index of the sheets. Section sheets focus on cross-sectional views of the project and are specific to particular aspects without serving the purpose of an index. Profile sheets show the vertical alignment and grades of the project elements but are also not designed to function as a directory of the plan set. Therefore, the key sheet is specifically designed to facilitate quick reference, making it the correct answer.