CHAPTER 3
182
Syntax
Multiple-Byte Strings in File Specifications
In PDF 1.2 or higher, a file specification may contain multiple-byte character
codes, represented in hexadecimal form between angle brackets (
<
and
>
). Since
the slash character
< 2F >
is used as a component delimiter and the backslash
< 5C >
is used as an escape character, any occurrence of either of these bytes in a
multiple-byte character must be preceded by the ASCII code for the backslash
character. For example, a file name containing the 2-byte character code
< 89 5C >
must write it as
< 89 5C 5C >
. When the application encounters this
sequence of bytes in a file name, it replaces the sequence with the original 2-byte
code.
3.10.2 File Specification Dictionaries
The dictionary form of file specification provides more flexibility than the string
form, allowing different files to be specified for different file systems or
platforms, or for file systems other than the standard ones (DOS/Windows, Mac
OS, and UNIX). Table 3.41 shows the entries in a file specification dictionary.
Regardless of the platform, consumer applications should use the
F
and
(beginning with PDF 1.7)
UF
entries to specify files. The
UF
entry is optional, but
it is also recommended because it enables cross-platform and cross-language
compatibility.
TABLE 3.41 Entries in a file specification dictionary
KEY
TYPE
VALUE
Type
name
(Required if an
EF
or
RF
entry is present; recommended always)
The type of PDF object
that this dictionary describes; must be
Filespec
for a file specification dictionary (see
(Optional)
The name of the file system to be used to interpret this file specification. If
this entry is present, all other entries in the dictionary are interpreted by the desig-
nated file system. PDF defines only one standard file system name,
URL
(see Section
names (see Appendix E). This entry is independent of the
F
,
UF
,
DOS
,
Mac
, and
Unix
entries.
FS
name