validation.xml && eg

<?xml version="1.0" encoding="ISO-8859-1" ?>
<!DOCTYPE form-validation PUBLIC
          "-//Apache Software Foundation//DTD Commons Validator Rules Configuration 1.1.3//EN"
          "http://jakarta.apache.org/commons/dtds/validator_1_1_3.dtd">
<form-validation>
<!--
     This is a minimal Validator form file with a couple of examples.
-->
    <global>
        <!-- An example global constant
        <constant>
            <constant-name>postalCode</constant-name>
            <constant-value>^\d{5}\d*$</constant-value>
        </constant>
        end example-->
    </global>
    <formset>
        <!-- An example form -->
        <form name="logonForm">
            <field
                property="username"
                depends="required">
                    <arg key="logonForm.username"/>
            </field>
            <field
                property="password"
                depends="required,mask">
                    <arg key="logonForm.password"/>
                    <var>
                        <var-name>mask</var-name>
                        <var-value>^[0-9a-zA-Z]*$</var-value>
                    </var>
            </field>
        </form>
    </formset>
    <!-- An example formset for another locale -->
    <formset language="fr">
        <constant>
            <constant-name>postalCode</constant-name>
            <constant-value>^[0-9a-zA-Z]*$</constant-value>
        </constant>
        <!-- An example form -->
        <form name="logonForm">
            <field
                property="username"
                depends="required">
                    <arg key="logonForm.username"/>
            </field>
            <field
                property="password"
                depends="required,mask">
                    <arg key="logonForm.password"/>
                    <var>
                        <var-name>mask</var-name>
                        <var-value>^[0-9a-zA-Z]*$</var-value>
                    </var>
            </field>
        </form>
   </formset>
</form-validation>