Custom fields
By default, EVA knows a lot of fields that can be configured for orders. You might however want to add a field that does not exist in EVA, and that is when custom fields become quite handy.
The Custom fields chapter in Admin Suite gives you an overview of all currently configured Custom fields of type User as well as the option to add new, or edit/delete existing ones. It hosts both order custom fields and orderline custom fields, and works similar to the custom fields chapter in the People module. The custom fields created here will also be displayed in the Shipments tab of purchase orders.

You need the CustomFields and CustomFieldTypes permissions to access this chapter.
Add Order or Orderline custom field
If you want to add an order or orderline custom field, you can add them in this chapter. How that is done is the same as everywhere else in EVA for custom fields.
Order custom field as tile in order options
Adding your order custom field BackendID
to the App:Order:ShowCustomFields
setting will, in turn, display it as a tile under your Order options on both POS and Companion apps.