Explanation
SAP S/4HANA stores low-level code in the following objects:
Bill of material (BOM), which is a structured list of components that make up a product or assembly.
Planning file, which is an internal table that contains information about materials that need to be planned by MRP. References: SAP S/4HANA Sourcing and Procurement | SAP Learning, Course S4525, Unit 1, Lesson 1.

Explanation
The Delivery Completed indicator in a purchase order item signals that no more goods receipts are expected for this item. Some consequences of setting this indicator are:
You can still post goods receipts of remaining quantities if you have not received the full ordered quantity yet. However, you cannot post goods receipts that exceed the ordered quantity.
The purchase order item is skipped when delivery reminders are generated by the system. Delivery reminders are messages that are sent to vendors to remind them of overdue deliveries orupcoming delivery dates. References: SAP S/4HANA Sourcing and Procurement | SAP Learning, Course S4520, Unit 2, Lesson 1.

Explanation
A subcontracting process involves sending components to a vendor who provides a service and returns an assembled or processed product. Some steps that can be part of this process are:
Post subsequent adjustment of component consumption, which means that you can correct the actual quantity of components consumed by the vendor after receiving the finished product.
Create an outbound delivery for components to be provided, which means that you can ship the components from your plant to the vendor's location using the shipping functionality.
Purchase components for direct delivery to the subcontractor, which means that you can order components from another vendor and have them delivered directly to the subcontractor without storing them in your own plant. References: [SAP S/4HANA Sourcing and Procurement | SAP Learning], Course S4520, Unit 4, Lesson 1.