problem1. describe the role of a DTD in XML
problem2. Illustrate, with the aid of exs, the difference between an XML document being "well formed" and "valid".
problem3. Determine three key differentiations between DTDs and XML Schemas.
problem4. What do you understand by the term Data Island? Give appropriate syntax to define one.
problem5. Describe the three types of Compositors used within the W3C XML Schema language that handle the order of individual elements.
problem6. Distinguish between Internal Entity and External Entity as used with DTDs. Illustrate your answer with simple exs.
problem7. ElementType is one of the major node uses to define an Element in XML Schema document. Describe the following five associated attributes name: