When formatting an index within DITA documentation, it’s important to consider both the visual presentation and the structure of the index to make it user-friendly and effective. Here are some guidelines for visually formatting an index in DITA:

1. Use a Clear Heading

Start the index section with a clear and descriptive heading. You can use a <title> element to define the heading of the index section. For example:

<title>Index</title>

2. Alphabetical Ordering

Indexes are typically organized alphabetically. You can use an <indexterm> element for each indexed term. The terms can be placed in alphabetical order, making it easy for users to find what they are looking for.

3. Hyperlinked Entries

Hyperlink the index entries to the corresponding sections in the documentation. This allows users to click on an entry and quickly navigate to the relevant content. You can use <indexterm> elements with the <primary> and <secondary> subelements to define the index entries and link them appropriately.

Example:

Here’s an example of how you can structure an index section in DITA:

<section id="index">
  <title>Index</title>
  <indexterm>
    <primary>Documentation</primary>
    <secondary>Formatting</secondary>
  </indexterm>
  <indexterm>
    <primary>Index</primary>
    <secondary>Structure</secondary>
  </indexterm>
  <indexterm>
    <primary>Navigation</primary>
    <secondary>Links</secondary>
  </indexterm>

In this example, the index section includes a heading, and index terms are organized alphabetically with primary and secondary entries. Each entry can be hyperlinked to the relevant content within the documentation.