In an XML file, each tag is the name of an element or attribute. In a DTD file, the tag <!ELEMENT> specifies the name of an element, and the tag <!ATTLIST> indicates the set of attributes for an element. In a schema file, <element name> specifies the name of an element and <attribute name> specifies the name of an attribute.
When you import an XML definition, the element tags become column names in the PowerCenter definition, by default.