| Rule | Parameter | Description | Example |
| required | No | Returns FALSE if the form element is empty. | |
| matches | Yes | Returns FALSE if the form element does not match the one in the parameter. | matches[form_item] |
| regex_match | Yes | Returns FALSE if the form element does not match the regular expression. | regex_match[/regex/] |
| differs | Yes | Returns FALSE if the form element does not differ from the one in the parameter. | differs[form_item] |
| is_unique | Yes | Returns FALSE if the form element is not unique to the table and field name in the parameter. Note: This rule requires Query Builder to be enabled in order to work. | is_unique[table.field] |
| min_length | Yes | Returns FALSE if the form element is shorter than the parameter value. | min_length[3] |
| max_length | Yes | Returns FALSE if the form element is longer than the parameter value. | max_length[12] |
| exact_length | Yes | Returns FALSE if the form element is not exactly the parameter value. | exact_length[8] |
| greater_than | Yes | Returns FALSE if the form element is less than or equal to the parameter value or not numeric. | greater_than[8] |
| greater_than_equal_to | Yes | Returns FALSE if the form element is less than the parameter value, or not numeric. | greater_than_equal_to[8] |
| less_than | Yes | Returns FALSE if the form element is greater than or equal to the parameter value or not numeric. | less_than[8] |
| less_than_equal_to | Yes | Returns FALSE if the form element is greater than the parameter value, or not numeric. | less_than_equal_to[8] |
| in_list | Yes | Returns FALSE if the form element is not within a predetermined list. | in_list[red,blue,green] |
| alpha | No | Returns FALSE if the form element contains anything other than alphabetical characters. | |
| alpha_numeric | No | Returns FALSE if the form element contains anything other than alpha-numeric characters. | |
| alpha_numeric_spaces | No | Returns FALSE if the form element contains anything other than alpha-numeric characters or spaces. Should be used after trim to avoid spaces at the beginning or end. | |
| alpha_dash | No | Returns FALSE if the form element contains anything other than alpha-numeric characters, underscores or dashes. | |
| numeric | No | Returns FALSE if the form element contains anything other than numeric characters. | |
| integer | No | Returns FALSE if the form element contains anything other than an integer. | |
| decimal | No | Returns FALSE if the form element contains anything other than a decimal number. | |
| is_natural | No | Returns FALSE if the form element contains anything other than a natural number: 0, 1, 2, 3, etc. | |
| is_natural_no_zero | No | Returns FALSE if the form element contains anything other than a natural number, but not zero: 1, 2, 3, etc. | |
| valid_url | No | Returns FALSE if the form element does not contain a valid URL. | |
| valid_email | No | Returns FALSE if the form element does not contain a valid email address. | |
| valid_emails | No | Returns FALSE if any value provided in a comma separated list is not a valid email. | |
| valid_ip | Yes | Returns FALSE if the supplied IP address is not valid. Accepts an optional parameter of ‘ipv4’ or ‘ipv6’ to specify an IP format. | |
| valid_base64 | No | Returns FALSE if the supplied string contains anything other than valid Base64 characters. |
