Can an optional field entered for an item, be also recognized in an order for that item?
Yes, Optional fields can be setup to be transferred automatically between documents and modules. In the above question, the optional field can be setup for an Inventory Item, and that field can follow that item and be referenced on an Order, Shipment and Invoice.
Firstly, setup the optional field in Common Services / Optional Fields. Then assign the optional field to the item in Inventory Control / Setup / Optional Fields - under the 'Optional Fields for Items'. The next step is to setup the same optional field in Order Entry / Setup / Optional fields under the 'Optional Fields for Order Details, Shipment Details, and Invoice Details' (each of these needs to be done individually).
Ensure the option for 'Auto Insert' is set to 'Yes'. That is all that is needed to have the optional field, that is attached to the inventory item, be transfered to any new order, shipment, or invoice detail line containing that item.