Minecraft wiki entry for Block_entity_format, associated text: : The block entity's root tag.
 hasBook: (May not exist) True if it has a book.
 page: (May not exist) The page the book is currently on, starting from 0.
 totalPages: (May not exist) The total pages the book has.
 book: (May not exist) The book item currently on the lectern.
Tags common to item stack[show]