Graham Keyarn in my example the only code on the main page is
<xt:include file="/data/{_$inc|default_file}"/>
when the page is first loaded $inc is not set so 'default_file' is included
the contents of 'default_file' are
<a class="btn btn-success btn-xs" href="?inc=lorem#">click me</a><br>
This is the content of the default file
The contents of 'lorem' are
<a class="btn btn-success btn-xs" href="?inc=nullam#">click me</a><br>
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Proin convallis nisi sed leo dignissim commodo...
The contents of 'nullam' are
<a class="btn btn-success btn-xs" href="?inc=nunc#">click me</a><br>
Nullam a odio arcu. Sed quis fermentum velit, eu feugiat urna. Donec bibendum, nisl non scelerisque congue...
and so on .
Each file contains the link to load the next one