While the "header" element is not required nor are any of its childen, it is recommended that it be included with a "mdDateTime" indicating the creation time of the instance document. While the "header" element is not required nor are any of its childen, it is recommended that it be included with a "mdDateTime" indicating the creation time of the instance document. DO NOT USE THIS ELEMENT! It is intended for use in generating documentation ONLY! This is the basic date and time field following the ISO 8601 specification.