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|3 Document Structure|
3.1 The XForms Namespace
3.2 Horizontally Applicable Markup
3.8 XForms and XLink
3.8.1 XLink Conformance and Examples
The XForms specification is an application of XML [XML 1.0] and has been designed for use within other XML vocabularies—in particular within XHTML [XHTML 1.0]. This chapter discusses the structure of XForms that allow this specification to be used with other document types.
The XForms namespace has the URI:
http://www.w3.org/2002/01/xforms. Any future Working Drafts are expected to use a different identifier,
though a final identifier will be allocated before XForms becomes a W3C
XForms Processors must use the XML namespaces mechanism [XML Names] to recognize elements and attributes from this namespace.
Every element defined in this specification declares attribute
id of type
xsd:ID—see the schema for XForms—this allows these elements to be
referenced via attributes of type
The XForms Processor must ignore any foreign-namespaced elements or attributes that are unrecognized.
Note that except where specifically allowed by the Schema for XForms, foreign-namespaced elements are not allowed as content of elements in the XForms namespace.
This section describes XForms element
model used as
a container for XForms elements defining the XForms model. The
containing document may
contain one or more
model elements. Element
model defines the
underlying model to which the XForms document binds user
model elements occur before the user interaction
markup. The content of element
model is typically not rendered. As an
model elements occur within element
html:head of an
XHTML document, whereas XForms user interface markup appears within element
<model extensionFunctions = list of QNames > <!-- Content: instance?, schema?, (privacy|submitInfo|bind|action|extension)* --> </model>
extensionFunctions - Optional list of XPath extension functions used by this XForms Model. It is an error to use an undeclared extension function.
model can contain the following
Defines skeleton instance document and holds initialization data if any—see 3.4 instance.
Defines schema for the instance—see 3.5 schema
Holds submit details—see 3.6 submitInfo
Establishes P3P properties—see 3.7 privacy
Extension elements if any—see 188.8.131.52 extension
<model xmlns="http://www.w3.org/2002/01/xforms" id="Person"> <instance xlink:href="http://example.com/cgi-bin/get-instance" /> <schema xlink:href="Schema-Questionnaire.xsd" /> ... </model>
instance contains a skeleton instance document that
provides initial instance data. The instance data may be defined inline or
obtained from an external URI.
<instance xlink:href = xsd:anyURI > <!-- Content: (##any) --> </instance>
xlink:href - Optional link to externally defined instance data
The content of the
instance element is arbitrary XML in any
The content of this element is treated as opaque
data. Authors must ensure that proper namespace declarations are used
for content within the
schema contains the schema defining the instance. The
schema may be defined inline or obtained from an external URI.
<schema xlink:href = xsd:anyURI > <!-- Content: ##other (though typically <xsd:schema>) --> </schema>
xlink:href - Optional link to an externally defined schema.
submitInfo encodes how, where and what to submit.
<submitInfo (single node binding attributes) action = xsd:anyURI mediaTypeExtension = "none" | qname-but-not-ncname : "none" method = "post" | "get" | qname-but-not-ncname : "post" version = xsd:NMTOKEN indent = xsd:boolean encoding = xsd:string mediaType = xsd:string omitXMLDeclaration = xsd:boolean standalone = xsd:boolean CDATASectionElements = list of xsd:QName replace = "all" | "instance" | "none" | qname-but-not-ncname : "all" > <!-- Content: XForms Actions --> </submitInfo>
single node binding attributes - optional selector enabling submission of a portion of the instance data
action - Required destination for submitting instance data.
mediaTypeExtension - Optional information describing the serialization format. This is in addition to the mediaType.
method - Optional indicator as to the protocol to be used to transmit the serialized instance data.
version - corresponds to the
indent - corresponds to the
encoding - corresponds to the
mediaType - corresponds to the
omitXMLDeclaration - corresponds to the
standalone - corresponds to the
CDATASectionElements - corresponds to the
replace - specifier for how the information returned after submit should be applied.
Many of these attributes correspond to XSLT attributes [XSLT].
Note that the XSLT attributes
doctype-public are not
supported in XForms processing.
Note also that
mediaTypeExtension is useful in cases where a media type alone is not sufficiently
precise. For instance, a SOAP envelope would not be adequately described simply by "text/xml", additional
information would be required.
privacy is used to associate a P3P
[P3P 1.0] policy reference with a particular form.
<privacy xlink:href = xsd:anyURI > <!-- Content: (##empty) --> </privacy>
xlink:href - Optional link to an externally defined P3P policyref file (not an actual policy).
XForms uses XLink [XLink] for linking and for defining
an explicit relationship between resources that may be either local or remote.
To this end, the XForms schema references the XLink namespace with sensible
defaults. Other than in the case of attribute
authors will not be required to explicitly write XLink-specific elements or
All XLinks in XForms are simple links. For further details, see 3.8.1 XLink Conformance and Examples.
An XForms processor is not required to implement full
XLink—correct behavior of the
xlink:href attribute (as defined
in this chapter) is sufficient. For example, an XForms Processor must accept
and correctly process the schema in both of the following:
<xforms:model> <xforms:schema xlink:href="URI-to-remote-schema.xsd" /> </xforms:model>
<xforms:model> <xforms:schema> <xsd:schema ...> <!-- Content: ... --> </xsd:schema> </xforms:schema> </xforms:model>
This second example is unusual in that the
element defaults an attribute
xlink:type="simple" but lacks an
xlink:href attribute to make the link
meaningful. In this situation, the XForms Processor should switch from
simple mode to
none mode for the element lacking attribute
compatibility with XLink, the second example should be explicitly authored as
<xforms:model> <xforms:schema xlink:type="none"> <xsd:schema...> <!-- Content: ... --> </xsd:schema> </xforms:schema> </xforms:model>
Notice the explicit override of the
If both inline content and external reference is provided, a processor must use the external reference and ignore the inline content.
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