2.2 Element Declarations

Element declarations in XSchemas are made using the XSC:ElementDecl element and its contents:

<!ELEMENT XSC:ElementDecl (XSC:Doc?, XSC:More?, (XSC:Ref | XSC:Choice | XSC:Seq | XSC:Empty | XSC:Any | XSC:PCData | XSC:Mixed), XSC:AttDef*)>
<!-- Name is the element name -->
<!ATTLIST XSC:ElementDecl
       Name NMTOKEN #REQUIRED
       id ID #IMPLIED
       Root (Recommended | Possible | Unlikely) "Possible">

The XSC:Name attribute identifies the name of the element, and is required. An element declaration would look like:

<XSC:ElementDecl Name="Species">
       ...additionalElementInformation...
</XSC:ElementDecl>

This declaration would declare an element named "Species", which would appear in an instance as:

<Species>...content...</Species>

The XSC:Name attribute must be unique within the set of elements, as it provides the name of the element as declared here, and is also used by other elements to refer to this element in their content model declarations. The XSC:Name attribute must also match the Name production in the XML 1.0 spec. (Effectively, this requires element names to begin with a letter, underscore, or colon.)

The XSC:id attribute, if it appears, must be unique within the document. This attribute may be used to uniquely identify this XSC:ElementDecl element for reference using XPointers and other tools.

The XSC:Root attribute provides authoring tools with a guide for which elements are likely root elements for documents. This is intended to simplify the choices presented to authors during document composition. Composition tools could use this to build a menu of likely starting points for a document.

Note that an element must declare a content model of some type, even if that content model is empty. Documentation (in the XSC:Doc element), non-XSchema extensions (in the XSC:More element) and attribute declarations (using XSC:AttDef elements) are optional.

Documentation about the element, additional extensions, content-model information, and attribute information are stored as sub-elements of the XSC:ElementDecl element. Documentation is covered in 2.6.1, Documentation Extensions. Additional extensions are covered in 2.6.2, Further Extensions. Content Models are covered in 2.3, Content Model Declarations, and attributes are covered in 2.4, Attribute Declarations.