WordPress at a glance
filter is not described

woocommerce_echeck_form_fields filter-hook . WC 1.0

Usage

add_filter( 'woocommerce_echeck_form_fields', 'filter_function_name_3908', 10, 2 );
function filter_function_name_3908( $default_fields, $id ){
	// filter...

	return $default_fields;
}
$default_fields
-
$id
-

Where the hook is called

WC_Payment_Gateway_ECheck::form()
woocommerce_echeck_form_fields
woocommerce/includes/gateways/class-wc-payment-gateway-echeck.php 56
$fields = wp_parse_args( $fields, apply_filters( 'woocommerce_echeck_form_fields', $default_fields, $this->id ) );

Where in WP core the hook is used WooCommerce

Usage not found.