WordPress at a glance
filter is not described

woocommerce_checkout_postcode_validation_notice filter-hook . WC 1.0

translators: %s: field name

Usage

add_filter( 'woocommerce_checkout_postcode_validation_notice', 'filter_function_name_6442', 10, 3 );
function filter_function_name_6442( $postcode_validation_notice, $country, $data[ $key ] ){
	// filter...

	return $postcode_validation_notice;
}
$postcode_validation_notice
-
$country
-
$data[ $key ]
-

Where the hook is called

WC_Checkout::validate_posted_data()
woocommerce_checkout_postcode_validation_notice
woocommerce/includes/class-wc-checkout.php 781
$errors->add( $key . '_validation', apply_filters( 'woocommerce_checkout_postcode_validation_notice', $postcode_validation_notice, $country, $data[ $key ] ), array( 'id' => $key ) );

Where in WP core the hook is used WooCommerce

Usage not found.