A header flag provides a means to place an informational entery at the top of a main section. For example if you want an entry at the top of the Events section that provides a general overview of how the event system operates, create a new comment as follows:
/**
*
* The event system is really cool, I know you'll love it!
*
* @event
* @header About Events
*/
It's kind of a hacky, but the @event flag tells use that this header is for the events section, and the @header "name" is used as the title for the section in the menu and on the page.
Also note that internally, we use the @order flag to yank this to the top of the list (so it appears first).