Exercise 5 effectively complete: world.html checkboxes behave as expected, world.js creates correct requests, world.php accepts requests and returns appropriate response. XML output does not display in world.html, but XML document is clearly received. XML document generated by world.php has errors: Some head_of_state names have '_' or other chars, which apparently cause incorrect writing to XML file. Aside from errors caused by this, however, XML is written to in correct format.