AndroidAPS/app/src/main/res/values/validator.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="error_only_numeric_digits_allowed">Only numeric digits are allowed.</string>
    <string name="error_only_numeric_digits_range_allowed">Only numeric digits within the range %1$s - %2$s are allowed.</string>
    <string name="error_this_field_cannot_contain_special_character">This field cannot contain any special character</string>
    <string name="error_only_standard_letters_are_allowed">Only standard letters are allowed</string>
    <string name="error_field_must_not_be_empty">The field must not be empty</string>
    <string name="error_email_address_not_valid">Email address not valid</string>
    <string name="error_creditcard_number_not_valid">Credit card number is not valid</string>
    <string name="error_phone_not_valid">Phone number not valid</string>
    <string name="error_domain_not_valid">Domain name not valid</string>
    <string name="error_ip_not_valid">IP Address not valid</string>
    <string name="error_url_not_valid">Web Url is not valid</string>
    <string name="error_notvalid_personname">Not a valid first or last name.</string>
    <string name="error_notvalid_personfullname">Not a valid full name.</string>
    <string name="error_date_not_valid">Format not valid</string>
    <string name="error_mustbe4digitnumber">Must be 4 digit number</string>
    <string name="error_mustbe6digitnumber">Must be 6 digit number</string>
    <string name="error_not_a_minimum_length">Not a minimum length</string>
    <string name="error_pin_not_valid">Pin should be 3 to 6 digits, not same or in series</string>

    <string name="fourdigitnumber" translatable="false">^\\d{4}</string>

</resources>