====== Terms and definitions ======
===== Unit loads =====
**Storage Unit loads** are the containers used for the storage of stock.  Usually this will be a pallet but can be any container.  Unit loads will have a unit load number.

**Phantom Unit loads** are where the unit load number is the same as the name of the location where the unit load is stored.   Phantom unit loads are created by the WMS when goods are stored directly on to a location without already being on a unit load.

**Goods out unit load** is a unit load that is created during the picking process.  Goods out unit loads contain goods destined for delivery to a customer.

**Mixed unit loads** are unit loads that contain more than one stock item.   
===== Locations =====
**Storage locations** are locations that are used for storing stock.  Any stock can be stored in a storage location.  ''Storage locations'' can have a specific ''capacity'' (measured in the number of unit loads).  However, most locations should be set to a capacity of 1.

**Racks** are identical to physical racks in the warehouse.   Many locations will make up one rack.  Racks are the primary method of ordering the locations around the warehouse.

**Picking location** is a special type of storage location reserved for a particular stock item.  Only stock items that are assigned to the picking location are allowed to be stored.  A single picking location can be assigned to many stock items.  The ''max qty'' on a picking location is the number of stock items what will fit in this picking location.

**Free picking location** is a special type of picking location where the the stock count is calculated from storage unit loads and the current ''stock on hand''. 

**GOODS-IN** is a special location where unit loads being their tour of the warehouse.

**GOODS-OUT** is a special location where goods and unit loads end their tour of the warehouse.

**CLEARING** is a special location where unit loads are held.  This might be while they are returned to stock or processed for disposal.

===== Free Picking Locations =====

Free picking locations do not hold stock.  They are place holders for a picking location.  They are also the end of the tour for stock items through the warehouse.  Where as normally a stock item's last step in the warehouse tour would be at the point of picking, the last step in the tour for an item in a free picking location is when the item is replenished into the free picking location.

Free picking locations make it possible to have self-service areas in the warehouse where customers can pick up stock without the need to create a picking list.

<wrap em>Suppose:  the stock in a free picking location is the ''stock on hand'' less ''the stock on unit loads''</wrap>

In the simplest sense the above statement is true.  However, stock in the ''checkout'' area is reserved, and already removed from the ''stock on hand''.

The actual calculation for the amount of stock in a free picking location is as follows;


<wrap em>SoH - SoUL + SiC - Picked = Stock in Free Picking Locations.</wrap>

where:

  * **SoH** is the stock on hand
  * **SoUL** is the total stock on unit loads.
  * **SiC** is the stock in the checkout area.
  * **Picked** is the stock that has been picked, but yet to be invoiced.