What is the difference between ATR,ATP,PTO,ATO and ATT

Available To Reserve (ATR)

The quantity of on-hand stock available for reservation. It is the current on-hand stock less any reserved stock.

Available To Transact (ATT)

Quantity on hand less all reservations for the item which may be transferred within or out of inventory

Assemble to Order – (ATO)

The product or Service is Assembled on the receipt of the Sales order. That is, the finished goods are created by combining with the other product parts only when an sales order is placed.Eg : Assume car manufacturing company, which has an assembling unit where all its individual components are either manufactured or purchased externally.

Pick to order- (PTO)

The product or services are picked from their locations using pick slip on receipt of the sales order.That is , the location and the product parts used to generate the finished goods are already predefined.Eg : Assume car manufacturing company, Which has certain parts manufactured in Germany, others in US and so on. So the total lead time would be to asses the time for bringing in these parts to the assembling unit.