Cardinality

As shown in the following table, the DTD syntax allows you to specify a cardinality (the number of times an element can appear within an XML document) for elements using the following modifiers: question mark (?), plus sign (+), and asterisk (*), or none. Elements with a cardinality, or occurrence, specified in a DTD map only to Integration Components. The Cardinality property in the Integration Component within Siebel CRM maps to the specified cardinality information in the DTD.

DTD Element Occurrence Operator	Description	Integration Component Cardinality Property	Description
None	Appears once	Not applicable	Not applicable
?	Appears 0 or once	Zero or One	Appears 0 or once
+	Appears one or more times	One or More	Appears one or more times
*	Can appear 0 or more times	Zero or More	Can appear 0 or more times
No modifier	Appears once	One	Appears once

The specification for DTDs supports using parentheses to express complex hierarchical structures. For example:

<!ELEMENT rating ((tutorial | reference)*, overall)+ >

The DTD Wizard uses the operator (?, *, +, or "none") closest to the child element as that child element’s cardinality. In addition, the DTD Wizard will ignore such grouping by parentheses as illustrated in the preceding example.