"Mark for TOC" (feature request)

Most books on the Internet Archive don't have a table of contents. On the OpenLibrary page for the specific book anyone can add one, but figuring out page numbers and remembering them together with titles can be a hassle (e.g. when page numbers are invisible or missing).

I imagine and hereby propose a button or link in the BookReader that marks a page as the start of a new chapter or section. When the button or link is clicked, a text field could ask for the title of the chapter and if applicable the nesting level of the section (chapter, section, subsection, subsubsection / h1, h2, h3).