XFA Specification
New XFA Template Features
969
Note that XFA 2.1 also requires XFA-SOM expression parsers to support an escape notation using “\”
(backslash) to escape the special meaning of “.” inside SOM expressions. In addition scripts written in
FormCalc (“FormCalc
require special handling of references to data nodes
having names containing the “.” character. See
“Using SOM Expressions in FormCalc” on page 98
for more
information.
Support for xsi:nil, version 2.1
The original XML specification
[XML1.0]
does not provide a way to distinguish between elements and
attributes that contain a zero-length string ("") and those which have no value at all assigned to them (null
values). This distinction is important in many applications. Later the [XML-Schema] standard introduced a
notation to represent values which are truly null. XFA 2.1 supports the representation of null values in data
using the notation defined by the XML-Schema, the
xsl:nil
attribute. However it is still
implementation-defined whether a particular XFA processor supports null values as distinct from
zero-length strings or not. See
“Data Values Representing Null Data” on page 130
about null-value handling.
Data Mapping (Data Loading)
New grouping transform, version 2.1
A new grouping transform has been added in XFA 2.1. This transformation allows for contiguous related
data items to be grouped automatically into a hierarchical structure, as though they had been wrapped
inside an enclosing element. This added structure makes it possible to take maximum advantage of XFA’s
intelligent merging and layout. See
“Extended Mapping Rules” on page 362
for more information.
Support for references in image data, version 2.1
Image data may now include hypertext references to content. Depending on the trusted nature of the
source of such hypertext references, the image data may be loaded into the XFA Data DOM.
Specifying data attributes to use for naming nodes in the XFA Data DOM, version 2.1
The config element can specify the data attribute from which the data loader obtains the node name,
rather than using the data element name. This config attribute is useful in situations where the element
names are not meaningful.
See “The nameAttr Element” on page 381.
Data Unloading
Use of data description when writing out XML, version 2.1
When loading data from XML XFA does not need to know the schema of the input XML data document.
However when unloading to XML, XFA 2.1 allows for the use of a schema to control the form of the output
XML data document. When no schema is supplied the behavior is unchanged from previous versions. The
schema, if present, is contained in an XFA Data Description as described in
“Unloading Node Type
Information” on page 138.
See
“Data Values Representing Null Data” on page 130
for a detailed
description of the way in which the data description is applied when unloading.