moodle/lang/en_utf8/form.php

<?php
$string['denotesreq']='$a denotes you must supply a value in this field.';
$string['requiredelement']='You must supply a value here.';
$string['nonexistentformelements']='Trying to add help buttons to nonexistent form elements : $a';
$string['nomethodforaddinghelpbutton']='There is no method for adding a help button to form element $a->name (class $a->classname)';
//error messages for standard rules
$string['err_required']='You must supply a value here.';
$string['err_maxlength']='You must enter not more than $a->format characters here.';
$string['err_minlength']='You must enter at least $a->format characters here.';
$string['err_numeric']='You must enter a number here.';
$string['err_rangelength']='You must enter between {$a->format[0]} and {$a->format[1]} characters here.';
$string['err_email']='You must enter a valid email address here.';
$string['err_lettersonly']='You must enter only letters here.';
$string['err_alphanumeric']='You must enter only letters or numbers here.';
$string['err_nopunctuation']='You must enter no punctuation characters here.';
$string['err_nonzero']='You must enter a number not starting with a 0 here.';
$string['err_numeric']='You must enter a number here.';

?>