Editing XFA (section)

===Packaging===
XFA forms can be created and used as PDF 1.5 - 1.7 files or as XDP (XML Data Package). The format of an XFA resource in PDF is described by the XML Data Package Specification.<ref name="iso32000" /> PDF may contain XFA in XDP format, but XFA may also contain PDF.<ref name="xfa-adobe" />

When the XFA (XML Forms Architecture) grammars used for an XFA form are moved from one application to another, they must be packaged as an XML Data Package. The XDP may be a standalone document or it may in turn be carried inside a PDF document.<ref name="xfa25" />

XFA Form packaging variants (using XDP): 
* as a '''standalone XML Data Package (XDP)''' (.xdp file) which can optionally also include a PDF file 
* '''inside a regular PDF Document''' - used for static forms - XFAF. 
* '''inside a "Shell PDF"''' - used for the "full XFA" form (dynamic or traditional static) - A Shell PDF file contains only a minimal skeleton of PDF markup plus the complete XFA content, any fonts and images needed for rendering of the form. It minimizes the file size and the rendering overhead is moved from the server to the client.

Packaging an XDP within PDF has the advantage that it is more compact, because PDF is compressed. XDP in PDF can be digitally signed in ways that a standalone XDP cannot.

In contrast, packaging form components within an XML container (XDP) makes it easy for standard XML applications to work with XFA forms. The XML components are human readable and easy editable (in contrast with PDF source code). When in XDP form, an XFA document may be validated using schemas attached to XFA specification.