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XDP Specification
This chapter contains a narrative description of the XML Data Packaging (XDP) grammar (“About
Grammar”)
and a reference for the XDP root element and XDP packets (“XDP
About the XDP Grammar
XDP is an XML grammar that provides a mechanism for packaging XFA components within a surrounding
XML container. Such XFA components may include a PDF document, PDF subassemblies (annots and
data), XFA form data, and custom XFA components. Packaging XFA components within an XML container
may be important for XML-based applications that support XFA.
Role of XDP
The XFA components come from various sources, each corresponding to a different type of XML grammar,
language (PDF), or language subassembly (annots and PDF data). In some cases, the XFA components are
serialized from a DOM representation (datasets). In other cases, the XFA components come from file-based
representations (templates). The source of a particular XFA component depends on whether the
in-memory representation may have changed during a session.
When an XFA processing application is requested to submit or export XFA components, it packages those
components as an XDP document (below left) or as a single PDF document (below right). XDP and PDF can
represent the same XFA form component; however, they differ in their root nodes and in the compliance
with XML. That is, XDP is XML-compliant, while PDF is not.
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