The element Element
The element element is used to declare child elements of an element. Thus, the element element is always a child element of either an ElementType element (which defines elements) or a group element. Just as you could for the element element in the W3C schema, you can define the number of occurrences of an element child element.
With BizTalk schemas, you will also use the minOccurs and maxOccurs attributes. In this case, minOccurs can only be 0 or 1. If minOccurs is 0, the element is optional; if it is 1, the element must occur once. The maxOccurs attribute can only be 1 or an asterisk (*). If maxOccurs is 1, the element can appear at most once; if it is *, the element can appear an unlimited number of times. This is different from the W3C schema, which allows any value to be assigned to minOccurs and maxOccurs.