anchor.diff:  
     USE iso_c_binding
   
  -  TYPE(datetime)  :: a
  +  TYPE(datetime)  :: a,b
     TYPE(timedelta) :: td
     TYPE(clock)     :: c
   
  
positive.code:                  'datetime == datetime')
    n = n+1
  
    tests(n) = assert(datetime(2013,1,2,3,4,5,6) &
                   /= datetime(2014,1,2,3,4,5,6),&
                   'datetime /= datetime')
  
negative.code:   n = n+1
  
    a = datetime(2014,1,1,0,0,0,tz=6)
    b = a-timedelta(hours=6)
    b % tz = 0
    tests(n) = assert(a % utc() == b,'datetime % utc(), +0600')
    n = n+1
  
    a = datetime(2014,1,1,0,0,0,tz=-6)
    b = a+timedelta(hours=6)
    b % tz = 0
    tests(n) = assert(a % utc() == b,'datetime % utc(), -0600')
    n = n+1
    !---------------------------------------------------------------------
  
  