Adobe Acrobat SDK
Syntax (Chapter 3 in PDF Reference)
Adobe® Supplement to the ISO 32000
3.6.4 Extensions to PDF 24
that it may contain developer-specific PDF properties that extend a particular base version of the PDF
specification.
The extensions dictionary enables developers to identify their own extensions relative to a base version of
PDF. Additionally, the convention identifies extension levels relative to that base version. The intent of this
dictionary is to enable developers of PDF-producing applications to identify company-specific
specifications (such as this one) that PDF-consuming applications use to interpret the extensions.
The intent of the extensions convention is two-fold:
●
Enable developers of PDF-producing applications to identify the use of company-specific extensions
they have added to a PDF document and to associate those extensions with their own
publicly-available specifications.
●
Enable developers of PDF-consuming applications to determine which extensions are present in a PDF
document and to associate those extensions with the specifications that describe them.
To avoid collisions over company names and company-specific extension names, ISO provides the prefix
name registry. The
prefix registry
is
used to designate a 4-character, case-sensitive prefix that identifies a
company or other entity. This prefix is used for company-specific version identifiers. Additionally, these
prefixes are used to create second-class names of the form ACME_aPropertyName. This registry is available
from the Prefix Registry link in the Related Resources panel at the following Web page:
http://www.adobe.com/go/ISO32000Registry
Table 3.25a shows the entries in an extensions dictionary, where each
Prefix name
entry is a registered
prefix. The extensions dictionary is the value of the
Extensions
entry in the document catalog. (See
Table 3.25 on
page 23
.) The extensions dictionary is part of ISO 32000 (See Section 7.12, “Extensions
Dictionary.”)
TABLE 3.25a Entries in the extensions dictionary
KEY
SUBTYPE
DESCRIPTION
Type
name
(
Optional
) The type of PDF object that this dictionary describes; shall be
Extensions
for an extensions dictionary.
Prefix
name
dictionary
A developer extensions dictionary representing the extensions added
by a developer. See
“Table 3.25b Entries in a developer extensions
dictionary” on page 25
.
The prefix name registry is available at
http://www.adobe.com/go/ISO32000Registry
Select from the Prefix Registry link in the Related Resources pane.
For information about prefix names, see Appendix E of the
Reference, sixth edition, version 1.7
.
