Stock is a very simple aspect that allows processes to add any objects to a stock and later on get them from that stock.

The stock mechanism cares that the process cannot get other objects from the stock than the ones that are put in.

Also the stock mechanism allows to count the number of articles of a kind.

The stock business object model is very simple. There's only one stock object for every kind of stock that is distinguished in the business model area.
An additional service therefore must be the administration of stocks.

As soon as more complicated stock-structures are needed, a new variant of the server can be designed and implemented.