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                                       1079
SECTION G.6                                                       Up dating Example



Example G.9 shows the lines added when the file was saved. Note that objects
with identifiers 8 0 and 9 0 have been deleted, as can be seen from the fact that
their entries in the cross-reference section end with the keyword f.

Example G.9

  7 0 obj
     [ 10 0 R
       11 0 R
     ]
  endobj

  xref
  0 1
  0000000008    65535 f
  7 3
  0000001978    00000 n
  0000000009    00001 f
  0000000000    00001 f

  trailer
      << /Size 12
          /Root 1 0 R
          /Prev 1855
      >>
  startxref
  2027
  %%EOF

The cross-reference section added at this stage contains four entries, representing
object number 0, the Annots array, and the two deleted text annotations.

• The cross-reference entry for object number 0 is updated because it is the head
  of the linked list of free entries and must now point to the entry for the newly
  freed object number 8. The entry for object number 8 points to the entry for
  object number 9 (the next free entry), while the entry for object number 9 is the
  last free entry in the cross-reference table, indicated by the fact that it points
  back to object number 0.
• The entries for the two deleted text annotations are marked as free and as
  having generation numbers of 1, which are used for any objects that reuse these
  cross-reference entries. Keep in mind that, although the two objects have been
  deleted, they are still present in the file. It is the cross-reference table that
  records the fact that they have been deleted.

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