Question:

(a) Describe the differences between a URI, a URN and a URL.

(b) What are the five basic syntax rules for a well-formed XML document?

(c) Provide four uses of DTDs.

(d) Consider that there is a special kind of paper that must have a title, an author and a body. We assign the author a unique ID and can include his or her address as an optional attribute. The body consists of one or more chapters, followed by a series of references. Because this paper belongs to the company "XYZ international," a copyright claim may appear in the paper.

Write a DTD to define the above structure for documents of type docpaper.