An S, S-1 Inventory Policy means that as soon as we sell one part we place an order for another.
This policy is common for for:
long lead time
service parts in industries such as aerospace.
10 service parts in stock. We sell
one and immediately place an order for another.
9 in stock and
1 in flight.
We sell another and immediately place an order. We now have
8 in stock and
2 in flight.
Sell another and immediately place an order. We now have
7 in stock and
3 in flight.
As we can see we what we have on hand and what we have in flight will always equal