I have an English site that I'd like to expand so that it can take care of German, Spanish, and French speakers. In particular, there's some user input that I verify using the regex:


along with preg_match to check if the user has entered letters, digits and some acceptable characters. Is there a summarized document of additional characters that are "letters" for these other languages? And, being my first foray into the international, what would be the easiest way to then actually type out these characters (such as an accented e or a)?

Danke, Gracias, and Merci,