PDF Explained

Chapter 7. Document Metadata and Navigation

In this chapter, we discuss four topics related not to the visual appearance of a PDF document, but to the ancillary data which may also be included for interactive, onscreen use of documents, and the metadata used to carry extra information with a document for use by programs in a PDF workflow.

Destinations

Data structures defining a position within a file. They can be used to specify where a bookmark or hyperlink points to. Bookmarks (properly called the document outline) are used as a table of contents for the document.

XML Metadata

A stream containing an XML file in a specified format, containing some of the same metadata as the document information dictionary, together with additional fields.

File Attachments

Allow whole files to be encapsulated in a document, much like an email attachment.

Annotations

Allow text and graphics to be applied on top of a PDF page, separate from the main page content, for display by onscreen readers. One particular kind of annotation is the hyperlink, which allows a user to click somewhere on a page and be redirected to a destination elsewhere in the file.

Bookmarks and Destinations

A document’s bookmarks (properly called the document outline) are a tree of entries (typically titles of chapters, sections, paragraphs etc.) which can be clicked on in a PDF viewer to move around the document. Each entry has some text and a destination describing where it links to.

Destinations

A destination defines a place ...