WordPress at a glance
action is not described

woocommerce_email_before_order_table action-hook . WC 1.0

Usage

add_action( 'woocommerce_email_before_order_table', 'action_function_name_6817', 10, 4 );
function action_function_name_6817( $order, $sent_to_admin, $plain_text, $email ){
	// action...
}
$order
-
$sent_to_admin
-
$plain_text
-
$email
-

Where the hook is called

In file: /templates/emails/plain/email-order-details.php
woocommerce_email_before_order_table
woocommerce/templates/emails/plain/email-order-details.php 20
do_action( 'woocommerce_email_before_order_table', $order, $sent_to_admin, $plain_text, $email );
woocommerce/templates/emails/email-order-details.php 22
do_action( 'woocommerce_email_before_order_table', $order, $sent_to_admin, $plain_text, $email ); ?>

Where in WP core the hook is used WooCommerce

woocommerce/includes/gateways/bacs/class-wc-gateway-bacs.php 72
add_action( 'woocommerce_email_before_order_table', array( $this, 'email_instructions' ), 10, 3 );
woocommerce/includes/gateways/cheque/class-wc-gateway-cheque.php 48
add_action( 'woocommerce_email_before_order_table', array( $this, 'email_instructions' ), 10, 3 );
woocommerce/includes/gateways/cod/class-wc-gateway-cod.php 49
add_action( 'woocommerce_email_before_order_table', array( $this, 'email_instructions' ), 10, 3 );