1. 1 Internal DTD External DTD

2. 2 Internal DTD ]> Tove Jani Reminder Don't forget me this weekend

3. 3 External DTD Tove Jani Reminder Don't forget me this weekend!

4. 4 DTD Element Ordering is Important in DTD This is an XML document Not a valid document This is an XML document Root Element

5. 5 * arbitrary instances

6. 6 + One or several

7. 7 ? – zero or one instance

8. 8 |- one from many

9. 9 <!ELEMENT AAA (BBB | CCC ) Element: Element: wrong

10. 10 <!ATTLIST attributes aaa CDATA #REQUIRED bbb CDATA #IMPLIED>

11. 11 NMTOKEN type can contain only letters, digits and point [. ], hyphen [ - ], underline [ _ ] and colon [ : ] NMTOKENS – NMTOKEN plus white spaces

12. 12 ID type can contain only characters permitted for NMTOKEN and must start with a letter. No element type may have more than one ID attribute specified. The value of an ID attribute must be unique between all values of all ID attributes.

13. 13 <!ATTLIST CCC X ID #REQUIRED Y NMTOKEN #IMPLIED

14. 14 The value of IDREF attribute must match the value of some ID attribute in the document. The value of IDREFS attribute can contain several references to elements with ID attribute separated with whitespaces.

15. 15 <!ATTLIST AAA mark ID #REQUIRED <!ATTLIST DDD ref IDREFS #REQUIRED>

16. 16

17. 17 The values of true are yes, no and yes. The values of month are 8, 2 and 1.:

18. 18 An element can be defined EMPTY. In such a case it can contain only attributes but no text.