The Schema Element
Because the Schema element will be included within the body of the BizTalk document, it cannot really be considered a root element. Therefore, instead of calling the Schema element the root element, we will call it the document element-that is, the highest level element of the BizTalk document. The Schema element indicates the start of a schema definition.
Two namespace attributes should be associated with the Schema element. The first is urn:schemas-microsoft-com:xml-data. This namespace is used by applications such as the Internet Explorer 5 XML parser as a processing instruction to identify the Schema elements defined in the sample DTD at the beginning of this section. This is the default namespace, so you do not have to prefix all the Schema element names with a namespace name. The second namespace attribute is urn:schemas-microsoft-com:datatypes. This namespace is used by applications to include all the data types associated with schemas. The data types listed in the dataTypes entity in the sample DTD are the currently allowable data types for elements.
Our sample DTD allows the following elements to be child elements of the Schema element: AttributeType, ElementType, and description. The description child element can occur once and provides a text description of the business document. Because the AttributeType child element belongs to the Schema element, this element is similar to the attributeGroup element of the W3C schema in that it represents an element with document scope. Unlike the attributeGroup element, however, the AttributeType element allows you to define only a single type of attribute instead of a group of attributes. The ElementType child element is equivalent to the element element in the W3C schema and is used to define elements.
An example of a Schema element is shown here:
<Schema name="NorthwindSchema"
xmlns="urn:schemas-microsoft-com:xml-data"
xmlns:dt="urn:schemas-microsoft-com:datatypes">
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</Schema>