Opening-Auction-Only orders are similar to closing-auction-only orders, i.e., they are active only in the instrument states Opening Auction and Opening Auction Freeze. In all other instrument states, they are inactive, i.e., they can be entered, modified or deleted, but they are not available for matching, and they do not contribute to the published market data.
When the instrument enters the Opening Auction state, all Opening-Auction-Only orders become automatically active, and they receive a new priority timestamp. The Opening-Auction-Only order participates in the opening auction as any regular order.
Unexecuted Opening-Auction-Only orders are not automatically deleted by T7 after the Opening Auction is terminated. Instead, they become inactive. Note however that after the opening auction, further entry of Opening-Auction-Only orders with validity for the same day only, is prevented.
Opening-Auction-Only orders can be market orders or limit orders. The "Price/Reasonability Check" and the "Extended Price Range Validation" are never applied for Opening-Auction-Only orders.