APPENDIX E
E
PDF Name Registry
This appendix discusses a registry, maintained by Adobe for developers, that con-
tains private names and formats used by PDF producers or Acrobat plug-in ex-
tensions.
Acrobat enables third parties to add private data to PDF documents and to add
plug-in extensions that change viewer behavior based on this data. However,
Acrobat users have certain expectations when opening a PDF document, no mat-
ter what plug-ins are available. PDF enforces certain restrictions on private data
in order to meet these expectations.
A PDF producer or Acrobat viewer plug-in extension may define new types of
actions, destinations, annotations, security, and file system handlers. If a user
opens a PDF document and the plug-in that implements the new type of object is
unavailable, the viewer behaves as described in Appendix H, “Compatibility and
A PDF producer or Acrobat plug-in extension may also add keys to any PDF
object that is implemented as a dictionary, except the file trailer dictionary (see
create tags that indicate the role of marked-content operators
(PDF 1.2),
as
described in Section 10.5, “Marked Content.”
To avoid conflicts with third-party names and with future versions of PDF, Adobe
maintains a registry for certain private names and formats. Developers must only
add private data that conforms to the registry rules. The registry includes three
classes:
•
First class.
Names and data formats that are of value to a wide range of de-
velopers. All names defined in any version of the PDF specification are first-
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