[Exim] efficienty in filter constructs

I can't read, nor can my display handle, korean. I've got some filter
checks for those messages. I'm just wondering which construct is more
efficient :

   $h_Content-Type: is "text/html; charset=ks_c_5601-1987"
       or
   $h_Content-Type: is "text/html; charset=EUC-KR"

$h_Content-Type: matches "text/html; charset=(ks_c_5601-1987|EUC-KR)"


TIA,
-D

--

For society, it's probably a good thing that engineers value function
over appearance.  For example, you wouldn't want engineers to build
nuclear power plants that only _look_ like they would keep all the
radiation inside.
    (Scott Adams - The Dilbert principle)