name_form_field_regexp.php

<?php
//	$namepreg = '/^[a-zA-Z \'\-]+$/';

    $namepreg = '/^[a-zA-ZöüõäÕÄÖÜñÑĀāČčĒēĪīŠšŪūŽž \'\-]+$/'; // Latvian letters

	$mailpreg = '/^[A-Z0-9._%-]+@[A-Z0-9][A-Z0-9.-]{0,61}[A-Z0-9]\.[A-Z]{2,6}$/i';
	$phonepreg = '/^[\+0-9]+$/';
	
	if (!preg_match($namepreg, htmlspecialchars($firstName)))
	{
		$errorFields[] = 'firstName';
	}
	
	if (!preg_match($namepreg, htmlspecialchars($lastName)))
	{
		$errorFields[] = 'lastName';
	}