CHAPTER 3
184
Syntax
KEY
TYPE
VALUE
EF
dictionary
(Required if
RF
is present; PDF 1.3; amended to include the
UF
key in PDF 1.7)
A dictio-
nary containing a subset of the keys
F
,
UF
,
DOS
,
Mac
, and
Unix
, corresponding to the
entries by those names in the file specification dictionary. The value of each such key
is an embedded file stream (see Section 3.10.3, “Embedded File Streams”) containing
the corresponding file. If this entry is present, the
Type
entry is required and the file
specification dictionary must be indirectly referenced. (See implementation note 46
in Appendix H.)
Note:
It is recommended that the
F
and
UF
entries be used in place of the
DOS
,
Mac
, or
Unix
entries.
RF
dictionary
(Optional; PDF 1.3)
A dictionary with the same structure as the
EF
dictionary, which
must also be present. Each key in the
RF
dictionary must also be present in the
EF
dic-
tionary. Each value is a related files array (see “Related Files Arrays” on page 186)
identifying files that are related to the corresponding file in the
EF
dictionary. If this
entry is present, the
Type
entry is required and the file specification dictionary must
be indirectly referenced.
(Optional; PDF 1.6)
Descriptive text associated with the file specification. It is used
for files in the
EmbeddedFiles
name tree (see Section 3.6.3, “Name Dictionary”).
(Optional;
must be indirect reference; PDF 1.7)
A collection item dictionary, which is
used to create the user interface for portable collections (see Section 3.10.5, “Collec-
Desc
text string
dictionary
CI
3.10.3 Embedded File Streams
File specifications ordinarily refer to files external to the PDF file in which they
occur. When a PDF file is archived or transmitted, all external files it refers to
must accompany it to preserve the file’s integrity.
Embedded file streams (PDF 1.3)
address this problem by allowing the contents of referenced files to be embedded
directly within the body of the PDF file. For example, if the file contains OPI
(Open Prepress Interface) dictionaries that refer to externally stored high-
resolution images (see Section 10.10.6, “Open Prepress Interface (OPI)”), the
image data can be incorporated into the PDF file with embedded file streams.
This makes the PDF file a self-contained unit that can be stored or transmitted as
a single entity. (The embedded files are included purely for convenience and need
not be directly processed by any PDF consumer application.)