How hard is it to add a custom field to a sales order?
I’ll give you two examples:
1. I would like to have a “ship date” field, for instances when a customer wants the shipment of their order delayed until a specific date. (I would like this field to be only visible from the admin panel, not exposed to the customer.)
2. I would like to have a boolean flag added to an order that would not be exposed via any user interface. I would basically like to filter orders on this field using the Web Services API.