I saw that function at the wordpress site and another reference to it in the formatting.php file so I went looking for it. Here it is for reference;
/**
* Sanitizes a username, stripping out unsafe characters.
*
* Removes tags, octets, entities, and if strict is enabled, will only keep
* alphanumeric, _, space, ., -, @. After sanitizing, it passes the username,
* raw username (the username in the parameter), and the value of $strict as
* parameters for the 'sanitize_user' filter.
*
* @since 2.0.0
*
* @param string $username The username to be sanitized.
* @param bool $strict If set limits $username to specific characters. Default false.
* @return string The sanitized username, after passing through filters.
*/
function sanitize_user( $username, $strict = false ) {
$raw_username = $username;
$username = wp_strip_all_tags( $username );
$username = remove_accents( $username );
// Kill octets
$username = preg_replace( '|%([a-fA-F0-9][a-fA-F0-9])|', '', $username );
$username = preg_replace( '/&.+?;/', '', $username ); // Kill entities
// If strict, reduce to ASCII for max portability.
if ( $strict )
$username = preg_replace( '|[^a-z0-9 _.\-@]|i', '', $username );
$username = trim( $username );
// Consolidate contiguous whitespace
$username = preg_replace( '|\s+|', ' ', $username );
/**
* Filter a sanitized username string.
*
* @since 2.0.1
*
* @param string $username Sanitized username.
* @param string $raw_username The username prior to sanitization.
* @param bool $strict Whether to limit the sanitization to specific characters. Default false.
*/
return apply_filters( 'sanitize_user', $username, $raw_username, $strict );
}
I'm not an expert on .php but it looks to me like standard wordpress lets just about any character to be used with WordPress, provided $strict=false.
And, fwiw, i'm posting this here figuring that the people using SP are probably also WP literate and might be able to help. i'm not necessarily vying for admin help. the wordpress.org forums are very limited in the help that one can expect to find there so i thought it might be something we could discuss here. if it isn't appropriate to post these kinds of general WP questions then I won't do so again in the future.
Bart