Thanks lat9, but let me rephrase to be sure I understood what you're saying.

1-ZC naturally issues events that can be interrupted and triggers a new add-on behavior.

Quote Originally Posted by lat9 View Post
I am not an EO export, but it's a very popular plugins among my clients.

The current (4.1.4) version of EO includes a mock shopping-cart class, where the cart-related notifiers might be added; you'll need to review the functions where those top two notifiers are issued in the store-front class and then mimic that behavior in the mock-cart class.
2-EO has its own cart management class, so I have to add notifier calls to this class so that these new events calls my behavior.

Quote Originally Posted by lat9 View Post
The admin-console version of the order-class only supports order-instantiate, not create-order-from-cart (where the last notifier is issued store-front), so you'll need to review how that notifier is used by the plugin so that you can mimic that behavior within the admin-console handling.
3-ZC Admin side, and so EO does not makes regular orders but only loads existing orders, modifies (thanks EO), and replace the order in the tables.

Quote Originally Posted by lat9 View Post
Finally, you'll need to create an admin-console auto_loader to make sure that your attribute-calculator is loaded during the admin-level processing so that it's available to handle those notifications.
That is the easy part :-)

Reading you I just realized that these four events :
NOTIFIER_CART_CALCULATE_ATTRIBUTE
NOTIFIER_CART_ATTRIBUT_SELECT
NOTIFY_HEADER_SHOPPING_CART_OPTION_PRICE
NOTIFIY_ORDER_CART_FINISHED

are not in https://www.zen-cart.com/wiki/index....et_in_Zen_Cart.

Or are they and the website list is only (as stated) "Notifier points for Zen Cart 1.3.7".

In other words has the developer created its own events or are these regular ZC 1.5 events. I didn't saw that these could be custom events.