persisting form data during checkout ...

Thanks.

when does the order id become available. I guess, its not yet available when checkout starts -- i.e. in the checkout shipping page. I think an order is only generated once the checkout process is confirmed.

Currently, there exists functionality to continue shopping when a customer logs in and find items in a basket from a previous session. What kind of identifieris used to track the fact that a basket already exists -- perhaps a basket identifier.

I believe a logged-in customer's cart from a previous session is stored in the database, and retrieved when they re-login.

gjh42:

I believe a logged-in customer's cart from a previous session is stored in the database, and retrieved when they re-login.
The customer's shopping-cart "basket" contents are stored in the database. This includes products and attributes details only.