From the documentation:
<!-- Net:f:FileName -->
Includes a (html) file at this point of the web page. Similar to the Clarion "INCLUDE" command. Use this to include static bits of HTML, stored in static files on the disk, inside dynamic web pages.
Tip: If the file contains raw text, not formatted HTML, then you can wrap the tag with the <pre> Html tags. For example
<pre>
<!-- Net:f:disclaimer.txt -->
</pre>
Peter