Constructor Without parameter it is initialized to missing.
1933 if ( c_e(this%datetimemin%datetime) .and. c_e(that%datetime%datetime) .and. &
1934 this%datetimemin%datetime > that%datetime%datetime )
return
1935 if ( c_e(this%datetimemax%datetime) .and. c_e(that%datetime%datetime) .and. &
1936 this%datetimemax%datetime < that%datetime%datetime )
return