Orders for HK market

There are more order type in HK market than SGX. Do look up your brokage provider as they have a better explaination on this order types or HKEx.

Orders for Matching period

Both Auction orders, limit and market, can only be used during the matching period.

Auction market order
For auction market order, its a market order that will be filled at the prevailing market price during the matching period and enjoy a matching priority than auction limit order.

Auction limit order
For auction limit order, the price will only be filled at that price or better. After the matching period ends, the order will converted to a limit order. If the limit price deviate away from the current trading price by more that 9 bids or more, the order will be rejected. Thus one will need to monitor the order.

Orders after matching period

Both limit and enhance limit orders are orders that will be filled at a better price or the limit price submitted by you. So whats the different for enhance limit order? Oh, theres another Special Limit order as well.

Enhanced Limit Order (ELO):
An ELO allows matching of up to five price queues at the same time. The input order price of an ELO can be matched up to four spreads better than the best price on the other side of the market. Any unfilled quantity of an ELO after matching will be converted into a Limit Order at the input order price.

Special Limit Order (SLO):
A SLO matches up to five price queues (i.e. the best price queue and the next four queues each at one-spread away) as long as the traded price is not worse than the input limit price. Any unfilled quantity of an SLO after matching will be cancelled by AMS/3.

More information about ELO and SLO is available on the Hong Kong Stock Exchange (HKEX) web site.
Source: http://www.dbsvonline.com/English/index.asp

Think it will be better if there are numerical examples which show the working of ELO. Will update again.