DAISY—Structure Guidelines: Elements, Block Elements, Information Object Bridgehead
A bridgehead is used when a print book contains headings that are clearly not a part of the document hierarchy and, similarly, in the DTB would not be a part of the global navigation. Some documents, textbooks for example, use headings that are not tied to the normal sectional hierarchy.
The <bridgehead> tag is used to mark up a free-floating heading. It must be contained within one of the level elements. While <hd> and <h1> … <h6> are restricted to one occurrence per level or <level1> … <level6>, respectively, <bridgehead> has no such restriction. It should however be used only when it is clear that none of the structural headings is appropriate.
<h2>Chapter 3: The Mission</h2>
<bridgehead>Arriving by sea</bridgehead>
<bridgehead>Arriving by land</bridgehead>