Forum Moderators: phranque
The pipe character must be an ASCII or UTF-8 value of %7c, and not be some special UTF-16 or "high character-code" entity.
Note that it's possible that you should be using the pattern
RewriteRule ^site([a-z]+)\.(xml¦gz)$ siteindex/siteindex.php?m=$1&g=$2 [NC,L]
Note the use of [NC] to make the character-comparison case-insensitive, simplifying the pattern (and doubling the code speed), and the required escaping of the literal period (it is otherwise interpreted as a regex token matching *any* single character).
Note also the addition of the [L] flag for improved efficiency. Use of [L] on every rule is recommended, unless you have a specific reason not to use it in mind.
Jim