What is used in the back matter of a document to clarify or supplement information?

In a document, the appendix serves a critical role in the back matter by providing additional information that enhances or clarifies content presented in the main body of the text. It can include supplementary data, detailed explanations, statistical analyses, or other relevant material that, while important, would disrupt the flow of the main narrative if included there. This allows readers who seek deeper understanding or specific details to access this information without overwhelming the primary content of the document.

The other options, while they serve important functions, do not fulfill the role of providing supplementary information in the context of back matter. The table of contents merely lists the sections and subsections of a document, facilitating navigation. The glossary defines terms used in the document, helping readers understand specific terminology. An expanded definition offers a more in-depth interpretation of a term but isn't categorized as supplemental material in the back matter. Each has its purpose, but the appendix is specifically designed to house additional clarifying information.