symfony/symfony-docs — pull request #1946 by tPl0ch (2012-11-21 15:33:29+00:00)
Title: Added example of non standard 'X-Requested-With' HTTP header.

This example is giving an example on how to add a non standard header, and as well reminding the user to add a 'HTTP_' prefix, so the custom header gets sent when doing the request.