XML Reference: Siebel eBusiness Application Integration Volume V > XML Integration Objects and the DTD Wizard > How the DTD Wizard Creates XML Integration Objects >
Attributes include additional information related to an element, and can be either required or implied (optional) and may optimally have a default value. For example, an element might be a car with soundsystem, transmission, and doors as attributes. Soundsystem can be any text and is required; transmission is required because there is a default listed; other is optional. This would be expressed this way:
soundsystem CDATA #REQUIRED
transmission (automatic | manual | 5-speed-manual) "automatic"
other CDATA #IMPLIED>
Attributes are always mapped to component fields and are related directly to elements. The component field within Siebel application has the XML Style property set to Attribute.