User Guide | Setting Surcharge Session Data
Data is set to the cart session by using functions primarily from flexi carts standard library.
The data that can be set in the cart session includes data of items added to the cart, user localisation data and cart configuration settings.
Since many of flexi carts features can be set using either manually submitted data, or data retrieved from the database; there are often two versions of a function to set session data. Functions that update session data using the database are prefixed with the function name 'update_xxx', whilst functions that use manually set data are prefixed with the name 'set_xxx'.