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       APPENDIX F                                                             Linearized PDF



       • Named destinations. These objects include the value of the   Dests or Names
         entry in the document catalog and all the destination objects that it refers to.
         See Section F.4.2, “Opening at an Arbitrary Page.”
       • The document information dictionary and the objects contained within it.
       • The interactive form field hierarchy. This group of objects does not include the
         top-level interactive form dictionary, which is located with the document cata-
         log.
       • Other entries in the document catalog that are not referenced from any page.
       • (PDF 1.3) The logical structure hierarchy.
       • (PDF 1.5) The renditions name tree hierarchy.
       • (PDF 1.5) Embedded file streams.

F.2.10 Main Cross-Reference and Trailer (Part 11)

       Part 11 is the cross-reference table for all objects in the PDF file except those
       listed in the first-page cross-reference table (part 3). As indicated earlier, this
       cross-reference table plays the role of the original cross-reference table for the file
       (before any updates are appended) and must conform to the following rules:

       • It consists of a single cross-reference subsection, beginning at object number 0.
       • The first entry (for object number 0) must be a free entry.
       • The remaining entries are for in-use objects, which are numbered consecutive-
         ly, starting at 1.

       The startxref line gives the offset of the first-page cross-reference table. The Prev
       entry of the first-page trailer gives the offset of the main cross-reference table.
       The main trailer has no Prev entry and in fact does not need to contain any en-
       tries other than Size.

       Note: In PDF 1.5 and later, cross-reference streams (see Section 3.4.7, “Cross-Refer-
       ence Streams”) may be used in linearized files in place of traditional cross-reference
       tables. The logic described in this chapter, along with the appropriate syntactic
       changes for cross-reference streams, still applies.

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