Help+Manual's variables have several features that make them extremely powerful and flexible:

You can define variables as HTML variables or as plain-text variables

You can redefine user variables on a per-topic basis

You can redefine user variables for your entire project with publishing tasks

These features are particularly powerful when you are generating HTML-based output. For example, you can perform search engine optimization on a per-topic basis and you can add individual JavaScript code to the HTML templates of every topic. We are sure that you will come up with additional uses for this powerful feature experiment!

 

See also:

Redefining variables

Transforming your output with skins

Skins & redefining variables

HTML template variables (reference)