Application data is data that is associated with a connection through the use of the SIOCSAPPLDATA ioctl socket command. The SIOCSAPPLDATA IOCTL enables applications to associate 40 bytes of application-specific information with TCP sockets the applications own. This application data can also be used to identify socket endpoints in interfaces such as Netstat, SMF, or network management applications. When the SIOCSAPPLDATA IOCTL is issued, the request argument parameter must contain a SetApplData structure as defined by the EZBYAPPL macro. For more information about the SIOCSAPPLDATA IOCTL, see the miscellaneous programming interfaces Real-time TCP/IP network monitoring NMI information. In the remainder of this topic, this application-specific data is referred to as ApplData.