Adobe Acrobat SDK
Syntax (Chapter 3 in PDF Reference)
Adobe® Supplement to the ISO 32000
3.6.4 Extensions to PDF 25
Table 3.25b shows the entries in a developer extensions dictionary.
The PDF document that contains the following segment may contain the Adobe-specific extensions
relative to PDF version 1.7.
%PDF 1.7
<</Type /Catalog
/Extensions
<</ADBE
<</BaseVersion /1.7
/ExtensionLevel 3
>>
>>
>>
The PDF document that contains the following segment may contain ACME extension number 4, which is
relative to PDF version 1.7. It may also contain MyCo extension number 1002, which is relative to PDF
version 500 (a hypothetical PDF version number).
%PDF 1.7
<</Type /Catalog
/Extensions
<</ACME
Table 3.25b Entries in a developer extensions dictionary
KEY
SUBTYPE
VALUE
Type
name
(
Optional
) The type of PDF object that this dictionary describes; if
present, will be
DeveloperExtensions
for a developer
extensions dictionary.
BaseVersion
name (
Required
) A name that designates a version of the PDF
specification and that is syntactically consistent with the
Version
key in the
Catalog
entry. (See Section 3.6.1.) The name value 1.7
designates PDF version 1.7, as defined in
PDF Reference, sixth
edition, version 1.7
available from the
Adobe PDF Technology
Center
.
Note:
The version in a PDF file can be specified in two places. The
initial line in the file or in the Catalog. The
BaseVersion
value may differ from the version number on the header
line, or as supplied by the
Version
key in the Catalog. This
is because it reflects the version of the standard that is
extended and not the version of this particular file.
ExtensionLevel
integer
(
Required
) An integer that is used in conjunction with the
associated
BaseVersion
. The interpretation of this value is
defined by the developer. The value of
ExtensionLevel
for a
particular
BaseVersion
value shall increase over subsequent
extensions.
Note:
Developers can designate lower-order digits to represent
sub-levels. For example, the value 100 could represent 1.0,
or the value 101 could represent 1.1.