OTTO (OUCH To Trade Options) is a digital communications protocol that allows customers of the NASDAQ (National Association of Securities Dealers Automated Quotations) to conduct business in the options market. With OTTO, subscribers can integrate NASDAQ into their proprietary networks and place, execute or cancel orders.
OTTO, which is based on the same technology as the OUCH protocol, works by passing logical messages between the host and the client application. Inbound messages are processed in the order received. Each new order contains a token specifying the date and the name of the account. Once a token has been used, it automatically expires so it cannot be used again. When an order has been placed, executed or canceled and the action has been accepted by the host, an acknowledgment message is sent to the customer.