In Word for Microsoft 365, this feature is not used.

Word master document enables you to cross-reference items among several documents; create indexes, tables of contents, and lists that span several documents; easily assign consistent page numbering, headers, and another formatting across multiple documents; etc.
A book is ideally suited to the master document feature. Each chapter can be a subdocument, and the elements common to the entire book can be contained in the master document itself.

Writing simple and easy to understand documents is a unique ability that lays somewhere between art and science. Word for Microsoft 365 can help you to improve your writing skills by providing readability statistic metrics.

You can easily change the appearance of revision marks in your document. Track Changes dialog box gives you full control over the insertions, deletions, formatting, and other revision marks.

Sometimes you need to search for a comment or comments from specific reviewers.

You can easily view two Word documents using View side by side feature. Synchronous scrolling makes it extremely convenient.