Front End User Login Plugin (XML Or Database - ver: 3.0)

[hameau]

as a PHP-user ...

... you'll probably be familiar with preg. (Y)

From http://www.regular-expressions.info/php.html:

These functions are a PHP wrapper around the PCRE library (Perl-Compatible Regular Expressions). Anything said about the PCRE regex flavor in the regular expression tutorial on this website applies to PHP's preg functions. You should use the preg functions for all new PHP code that uses regular expressions. PHP includes PCRE by default as of PHP 4.2.0.