It is often very useful to want to reuse a certain set of macro calls in every passage,
or to reuse an opening block of text. You can do this by giving the passage the special
footer. All passages with these tags will have their source text included at the top
footer, the bottom) of every passage in the story, as if by an invisible (display:) macro call.
If many passages have the
header tag, they will all be displayed, ordered by their passage
name, sorted alphabetically, and by case (capitalised names appearing before lowercase names).