APPENDIX H
1104
Compatibility and Implementation Notes
specified by the
EFF
entry. In both Acrobat 6.0 and 7.0, if the security han-
dler indicates that document-level metadata is to be in plaintext, the meta-
data will not be encrypted. It is up to individual security handlers to store
their own flags that indicate whether document-level metadata should be
in plaintext.
30. Acrobat viewers do not support the ability for third-party security han-
dlers to specify
None
as a value for
CFM
.
31. In the file specification dictionary (see Section 3.10.2, “File Specification
RF
) must use the same crypt filter as the em-
bedded file (
EF
).
32. The value of the
EncryptMetadata
entry is set by the security handler
rather than the Acrobat viewer application.
33. Acrobat 5.0 and Acrobat 6.0 avoid adding a
Version
entry to the document
catalog and do so only if necessary. Once they have added this entry, they
behave in this way:
•
Acrobat 5.0 never removes the
Version
entry. For documents containing
a
Version
entry, Acrobat 5.0 attempts to ensure that the version specified
in the header matches the version specified in the
Version
entry; if this
is not possible, it at least ensures that the latter is later than (and there-
fore overrides) the version specified in the header.
•
Acrobat 6.0 removes the
Version
entry when doing a full (non-incre-
mental) save of the document.
34. In PDF 1.2, an additional entry in the document catalog, named
AA
, was
defined but was never implemented. The
AA
entry that is newly intro-
duced in PDF 1.4 is entirely different from the one that was contemplated
for PDF 1.2.
35. In PDF 1.2, an additional entry in the page object, named
Hid
, was defined
but was never implemented. Beginning with PDF 1.3, this entry is obso-
lete and should be ignored.
36. Acrobat 5.0 and later viewers do not accept a
Contents
array containing
no elements.