The structure of each node consists of one or more paragraphs with annotations to the right. The links offered in the right-hand column lead to internal links, more detailed discussions of an issue, or to external links. The numbers in the left-hand column are internal reference points, to which links may be pointed from outside the document (e.g., if you wanted to create a pointer to paragraph 3 of the Introduction, the last part of the URL would read: introd.htm#03).