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SECTION 10.7                                                             Tagged PDF



Real Content and Artifacts

The graphics objects in a document can be divided into two classes:

• The real content of a document comprises objects representing material origi-
  nally introduced by the document’s author.
• Artifacts are graphics objects that are typically not part of the author’s original
  content but rather are generated by the PDF producer application in the course
  of pagination, layout, or other strictly mechanical processes. Artifacts may also
  be used to describe areas of the document where the author uses a graphical
  background, with the goal of enhancing the visual experience. In such a case,
  the background is not required for understanding the content.

The document’s logical structure encompasses all graphics objects making up the
real content and describes how those objects relate to one another. It does not in-
clude graphics objects that are mere artifacts of the layout and production pro-
cess.

A document’s real content includes not only the page content stream and subsid-
iary form XObjects but also associated annotations that meet all of the following
conditions:

• The annotation has an appearance stream (see Section 8.4.4, “Appearance
  Streams”) containing a normal (N) appearance.
• The annotation’s Hidden flag (see Section 8.4.2, “Annotation Flags”) is not set.
• The annotation is included in the document’s logical structure (see Section
  10.6, “Logical Structure”).

Specification of Artifacts

An artifact can be explicitly distinguished from real content by enclosing it in a
marked-content sequence with the tag Artifact:

   /Artifact                                  /Artifact propertyList
      BMC                                        BDC
          …                or                        …
      EMC                                        EMC

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