Previous Next

                                                  182
        CHAPTER 3                                                                           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
                      implementation note 45 in Appendix H).

FS      name          (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
                      3.10.4, “URL Specifications”); an application or plug-in extension can register other
                      names (see Appendix E). This entry is independent of the F, UF, DOS, Mac, and Unix
                      entries.

Previous Next