Some connection-oriented transport protocols support the concept of expedited data, also referred to as urgent data or out-of-band data. Data sent with the MSG_OOB flag in the send() API is sent as expedited data, and the transport protocol makes every effort to deliver the data as quickly as possible. Often the data is delivered out of order so that it gets to the other application as quickly as possible. Applications interested in maximum portability should avoid expedited data since it is not supported by all transport protocols.