<you asked for it >
This option works exactly as documented.  However, I believe that it's
operation is not very useful.
 
When set to 'N', The quantity allowed to be entered in the Ship Qty field is
limited only by the Item's UOH.  So, if UOH is 10 and 5 orders come in
each requesting qty 10 of a given item, SO-A will allow a quantity of 10 to be
entered for each order in the Ship qty field.
 
This is the original way that DBA was designed to work and is a
perfectly acceptable way for some people.  This causes problems for us
because it does not control (during order entry) how
many items are actually available to ship now for each order.
 
When set to 'Y', the quantity allowed to be entered in the Ship Qty field is
limited by the calculation:
  Available to Ship = UOH - qty on SO - qty on BO.
 
qty on SO = total of all other order qty to Ship field
qty on BO = total of all other order qty on BO field
 
Generally speaking, the qty on BO field in a sales order specifies the
quantity of an item that has been ordered, but cannot be shipped because
of insufficient UOH.
 
This may be an immediate requirement, or a future requirement.
 
Consider the following examples:
 
1.  Item UOH = 10, on SO = 8, on BO = 5.
     on SO represents a previous order.
     on BO represents a previous order with a future requirement (meaning,
     even though sufficient stock exists, this 5 will come from a future
     receipt.)
 
     Entering a new order with an immediate requirement for 2 results in
     both being back-ordered.  This is because the 5 on BO already
     are considered in the calculation of available.
 
2.  A relatively large order is received for an item that is not normally stocked in depth.  
     (for example, UOH = 10, never really exceeds 20)
     An order is received for qty 50 and the order entry person sets
     all 50 on BO because purchasing is going to issue a PO specificity for
     this order.  Now another order is received for qty 5.  with the  
     existing calculation, all 5 items will be placed in the BO field.
 
I believe that when this option is set to 'Y', the calculation should ignore qty BO and only consider
Available Qty = UOH - qty on SO.  This would treat the qty BO as a future requirement.
If one does not consider qty on BO as a future
requirement, then they should set this option to 'N'.
</you asked for it >

... and it fulfills that requirement perfectly!!
 
The reality of our business (and I would think some others  ) is that  
there are times were an entire order must be shipped complete.  This is
already a problem on one level, because there is no 'Ship complete Only' flag built
into the Order header.
 
I would welcome an option to not consider current BO qty in the SO-A calculation
of available to ship.