Templating engines typically allow a means for passing data between templates. This makes it possible to abstract repeated content that differs slightly based on its specific context. For example, breadcrumb navigation might include HTML list markup that only differs on each page by the page title and link of the last list item.

It would be helpful if data could be passed to templates in ILLiad using <#INCLUDE> tags. A simple solution for just string data might look like <#INCLUDE filename="[the filename]" data="{foo: 'bar', foo2: 'bar2'}">, and then the variables foo and foo2 would be available somehow in the included template.

In the breadcrumb navigation example, you might have an include-nav-breadcrumb.html file that gets included on every template with <#INCLUDE filename="include-nav-breadcrumb.html" data="{title: 'ILL FAQs', url: '/illiad/illiad.dll?Action=10&Form=12'}">.