Here's the regex for the xs:dateTime datatype

["Costello, Roger L." <costello@mitre.org>]

(\-?[0-9]{4}\-(0[1-9]|1[0-2])\-(0[1-9]|[1-2][0-9]|3[0-1])T(0[1-9]|1[0-2]):(0[0-9]|[1-4][0-9]|5[0-9]):(0[0-9]|[1-4][0-9]|5[0-9])(\.[0-9]+)?(([\+\-]1[0-2]:(0[0-9]|[1-4][0-9]|5[0-9]))|Z)?)