XFA Specification
Chapter 12, User Experience
Accessibility and Field Navigation
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Signature Widget Produces a PDF Signature
A template designer uses the signature widget to allow the person filling out the form to create a PDF
digital signature. The person would select the signature widget after completing the form. PDF signatures
can achieve various levels of security, the most important of which is "integrity". A document with integrity
is called a document-of-record.
See “PDF Signatures” on page 416.
The PDF digital signature includes the template as well as the data so that it attests to what the user saw
and signed. The fact that the document has been signed is indicated in some implementation-defined
way in the visual representation of the signature widget. The presence of a signature does not by itself
prevent further changes to the data but if any such change is made the signature widget changes in
appearance to indicate that the document is no longer signed.
It is possible to apply multiple document-of-record signatures to the same form. Once multiple signatures
have been applied, a change to any data invalidates all of the signatures.
Accessibility and Field Navigation
XFA templates can specify form characteristics that improve accessibility and guide the user through filling
out a field.
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Traversal order. An XFA template may be defined with a traversal order, which allows the user to tab
from one field to the next (“Traversal:
Accelerator keys. An XFA template may include accelerator keys that allow users to move from field to
field, by typing in a control sequence in combination with a field-specific character (“Accelerator
Speech. An XFA template supports speech enunciation, by allowing a form to specify the order in
which text descriptions associated with a field should be spoken (“Speech
Visual aids. XFA template may specify text displayed when the tooltip hovers over a field or a subform
(“Other
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Traversal: Tabbing Order and Speech Order
The traversal (sequencing) capability of XFA forms simplifies navigation between objects on a form and
supports speech programs.
The traversal capability simplifies navigation by allowing a person filling out a form to more easily move
from one field to the next. The user initiates such movement by typing special characters such as tab,
up-arrow, or down-arrow, or by supplying the maximum number of characters allowed in a field.
The traverse capability of XFA forms allows speech programs to advance from one object to the next, after
they have completed reading the text associated with the container.
Traversal specifications are provided in
traversal
traverse
elements. Traverse specifications are properties of the following types of containers: subforms, exclusion
groups, fields, and draws.
Each
traverse
element contains an
operation
attribute that specifies a keystroke or event that
triggers traversal, and a traverse destination. The traverse destination is specified as a SOM expression or
as a script. In either case, the destination must resolve to a SOM expression for a valid layout object.
Default transition directions are defined for any omitted traverse operations.