A bookmark or outline item.
PDF documents typically provide a list of bookmarks for easy
navigation between pages. In Acrobat this navigation structure is
available under the Bookmarks tab. The PDF specification refers to
this structure as the document outline.
The document outline comprises of a hierarchy of bookmarks. The
bookmark at the top of the hierarchy is available via the Doc.Bookmark
property. Typically a bookmark triggers navigation to a particular
page but in some cases it may trigger a different and more complex
type of action.
Every bookmark holds a collection of all its child bookmarks. As
with all collections you can use the Count property to determine
the number of items contained and you can iterate through the
collection using the standard methods appropriate to the language
you are coding in.
ICollection<Bookmark>, IEnumerable<Bookmark>, IList,