Tap a section in a book's Contents to read it. From its menu you can edit the text, rename it or delete it. The book's menu adds a section at the end of the chapters, and publishes the book or returns it to draft.
Section text is edited as Markdown. Pictures and page breaks appear as [[Picture 1]] and [[Page break]] lines that you can move or delete. A section that uses underline, a different font or text size, or list items with line breaks can be read, renamed and deleted in the app but not edited there, so that formatting is never lost.
If a section changed somewhere else while you were editing, the app shows the latest version and lets you keep it or replace it. The first text change in each editing session keeps the previous text as a snapshot.