Formal markup is a Standard Generalized Markup Language (SGML) that an author can use to create fully compliant SGML help topics. It requires start and end tags for all elements. Additionally, the structure of each element must be explicitly tagged. Therefore, the number of tags increases significantly using formal markup. Although an author can enter formal markup using a standard editor, a structured editor is recommended.
New tools, called structured editors, are becoming available in response to the need to create SGML markup efficiently. Typically, a structured editor provides a context-sensitive menu. That is, the elements that appear in the menu dynamically change based on the location of the cursor in the document.
For example, if you are entering a list, then the menu contains only elements that are valid within the context of a list element. This built-in "intelligence" allows an author to create markup easily.
When an author chooses an element, such as section, head, or list, the editor generates the corresponding start, end, and any intermediate structural tags. For example, when an author selects a chapter element, the editor automatically inserts the intermediate tags required by this element. The author simply types the chapter title. Viewing the generated tags is optional; authors can suppress the tags.
Either markup approach-- shorthand or formal-- produces identical online information when compiled and displayed. Choosing which markup approach to use depends on the requirements for your help information and your available authoring tools.
If you intend to use formal markup, first read the chapters in Part 2 - The Author's Job to become familiar with the set of HelpTag elements. Although shorthand and formal markup share the same tag set, there are several important differences.
Chapter 8, Reading the HelpTag Document Type Definition, explains key components of the Document Type Definition (DTD) and shows you how to create formal markup. The complete HelpTag Document Type Definition appears in Appendix A.
The Developer's Kit includes the HelpTag Document Type Definition. The file is located in the /usr/dt/dthelp/dthelptag/dtd directory and is named helptag.dtd.