\begingroup

\catcode"C3=\active
\catcode"C5=\active
%
\def^^c3#1{%
	% not present anyway - doesn't matter
	\ifx#1^^a9^^e9\else % é - U+00E9 - eacute
	\errmessage{Hyphenation pattern file corrupted or ec encoding not supported!}
\fi}
\def^^c5#1{%
	\ifx#1^^93^^1b\else % œ - U+0153 - oe
	\errmessage{Hyphenation pattern file corrupted or ec encoding not supported!}
\fi}
%
% ensure all the chars above have valid lccode values
%
\lccode"E9="E9 % é - U+00E9 - eacute
\lccode"1B="1B % œ - U+0153 - oe

\patterns{
1cœ
.dé2s1œ
1mœ
1nœ
1sœ
}
\endgroup
