SECTION F.2
1031
Linearized PDF Document Structure
The first-page trailer must contain valid
Size
and
Root
entries, as well as any
other entries needed to display the document. The
Size
value must be the com-
bined number of entries in both the first-page cross-reference table and the main
cross-reference table.
The first-page trailer may optionally end with
startxref
, an integer, and
%%EOF
,
just as in an ordinary trailer. This information is ignored.
F.2.4 Document Catalog and Document-Level Objects (Part 4)
Following the first-page cross-reference table and trailer are the catalog dictio-
nary and other objects that are required when the document is opened. These
additional objects (constituting part 4) include the values of the following entries
if they are present and are indirect objects:
•
The
ViewerPreferences
entry in the catalog.
•
The
PageMode
entry in the catalog. Note that if the value of
PageMode
is
UseOutlines
, the outline hierarchy is located in part 6; otherwise, the outline
hierarchy, if any, is located in part 9. See Section F.2.9, “Other Objects (Part 9)”
for details.
•
The
Threads
entry in the catalog, along with all thread dictionaries it refers to.
This does not include the threads’ information dictionaries or the individual
bead dictionaries belonging to the threads.
•
The
OpenAction
entry in the catalog.
•
The
AcroForm
entry in the catalog. Only the top-level interactive form dictio-
nary is needed, not the objects that it refers to.
•
The
Encrypt
entry in the first-page trailer dictionary. All values in the encryp-
tion dictionary must also be located here.
Objects that are not ordinarily needed when the document is opened should not
be located here but instead should be at the end of the file; see Section F.2.9, “Oth-
information dictionary, and the definitions for named destinations.
Note that the objects located here are indexed by the first-page cross-reference
table, even though they are not logically part of the first page.