trouble with utf-8 chars & apache2 rewrite rules

Question

I see the post validating utf-8 in htaccess rewrite rule and I think that is great, but a more fundamental problem I am having first:

I needed to expand to handle utf-

Answer 1

work with CodeIgniter and utf-8 vietnamese (Tiếng Việt) file .htaccess:

RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^(.+[a-z,A-Z,0-9,ễ].+)$ index.php/$1 [L]

when url have 'ễn' then error => RewriteRule have 'ễ'