Saving Templates with CTRL+S is great

What does that do?

<li><label for="ctrl_content_show_signature"><input type="checkbox" name="content_show_signature" value="1" id="ctrl_content_show_signature" {xen:checked "{$visitor.content_show_signature}"} />
                    {xen:phrase show_peoples_signatures_with_their_messages}</label></li>
I am working on an add-on and found that in the core files. Why the input name is "content_show_signature" and the id is "ctrl_content_show_signature". Up until now I would use the same string from both. What does XenForo do with crtl_ ?