SP buyer order depth and details (of stock), page-22

Might of had an order only partial bought/sold and rather than cancel the order just amend to buy/sell one more.

Another reason, like myself I have done many times before. If I were to buy out a whole line on the buy side that cost me $11,000 and still having remaining units to buy with my order, I amend to 1 and place it way down the buy que. As I am with being with Comsec it would cost me $29.95 in brokerage. Amending the order allows me to further buy another $14,000 (through the amended order) for no cost. Obviously buying the same stock though.