dx:format 

string (like a regular expression) corresponding to the expected format for the element (like YYYY-MM-DD ...)

Element Information

Model

Used By

Element dx:type

Source 

<xs:element name="format" type="xs:string">
  <xs:annotation>
    <xs:documentation>string (like a regular expression) corresponding to the expected format for the element (like YYYY-MM-DD ...)</xs:documentation>
  </xs:annotation>
</xs:element>

Sample