APPENDIX H
1102
Compatibility and Implementation Notes
13. Acrobat viewers require only that the header appear somewhere within
the first 1024 bytes of the file.
14. Acrobat viewers also accept a header of the form
%!PS−Adobe−N .
n
PDF−M .
m
15. Acrobat viewers do not enforce the restriction on object numbers existing
in more than one subsection; they use the entry in the first subsection
where the object number is encountered. However, overlap is explicitly
prohibited in cross-reference streams in PDF 1.5.
16. Acrobat 6.0 and later do not use the free list to recycle object numbers;
new objects are assigned new numbers.
17. Acrobat viewers do not raise an error in cases where there are gaps in the
sequence of object numbers between cross-reference subsections. The
missing object numbers are treated as free objects.
18. Acrobat viewers require only that the
%%EOF
marker appear somewhere
within the last 1024 bytes of the file.
19. When creating or saving PDF files, Acrobat 6.0 limits the number of ob-
jects in individual object streams to 100 for linearized files and 200 for
non-linearized files.
20.
FlateDecode
is the only filter supported by Acrobat 6.0 and later viewers
for cross-reference streams. These viewers also support unencoded cross-
reference streams.
21. Byte addresses can be as large as needed to address an arbitrarily large PDF
file, regardless of the implementation limit for PDF integers in general.