1. Select the content to specify the bookmark or the location to insert the bookmark.
2. Click the Bookmark button in the Insert menu;
3. The bookmark dialog box pops up, and under "Book Signature", type the book signature.
4. Click the "Add" button, as shown.
Note: The book signature must start with a letter, and can contain numbers, but not spaces. You can use underscore characters to separate words, such as "abc" or "Bookmark _ 123".