Specifications

DescriptionData typeStatistic name
• Composite
CP2 data model
The CP2 data model (part of the metadata module) describes a class that inherits all functions
of the XMP data model and all functions of the Dataset class. The following subsections describe
the functions specific to the CP2 data model.
Overview
Since most Certified PDF 2 information is stored as XMP, the “CP2” data model inherits from the
“XMP” data model. Thus any XMP data model function can be invoked on a CP2 dataset as well.
A CP2 dataset is always embedded. It is not possible to create an external dataset with this data
model.
A CP2 dataset can either be read-only or writable. When a writable CP2 dataset is finalized, an
appropriate Certified PDF 2 signature is written to the backing file - in addition to updating the
XMP and CP2 data structures.
A CP2 dataset can be obtained for any PDF file, whether it is a valid Certified PDF 2 file or not.
This allows converting a regular PDF file into a Certified PDF 2 file.
A writable CP2 dataset can be “cleared”, removing all Certified PDF 2 related information. This
allows converting a Certified PDF 2 file into a regular PDF file.
File formats other than PDF are not supported, since Certified PDF 2 is tied to PDF.
Supporting the new CP2 data model requires:
Effects on the scripting API
• Adding semantics to a limited number of existing functions.
• Offering a range of new classes (and corresponding functions).
Compatibility
Since a PDF file with a valid GWG Proof of Preflight ticket is – by
definition – also a valid Certified PDF 2 file, the scripting API presented
in this document fully supports the GWG Proof of Preflight specification.
GWG Proof of Preflight
The scripting API does not support Certified PDF 1 files. In other words,
Certified PDF 1 files are treated as regular PDF files, and any Certified
PDF 1 data structures are ignored.
Certified PDF 1
Accessing XMP metadata
After obtaining a CP2 dataset, the Certified PDF 2 metadata stored in the XMP
packet must be accessed exclusively through the functions specific for the
Certified PDF 2
metadata
CP2 data model. Accessing any XMP metadata fields in the CP2 namespace
using the regular XMP access functions has undefined results.
Note: This allows the CP2 data model implementation to cache Certified PDF
2 information without immediate write-through to the XMP fields.
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