DT_MSG_INFO

appl_name: The name of the custom server that sent the message. A #define for APPL_NAME is provided in the system-generated header file for the custom server. If the message was sent by a state table, for example by a SendData action, this field contains a null string.
link_id: The identifier of the channel process that sent the message.
func_id: The identifier of the user function for which the message is intended. Each user function has a corresponding function ID of the form funcname_func_id. For example, the ID for the function x_proc() is x_proc_func_id.
key_part: An internal identifier for the message.
call_id: A numeric call identifier generated by the system. This identifier is passed by the channel process to the custom server and is used to associate a channel and a particular call.
This field was added for Version 2 Release 1 of IBM DirectTalk for AIX. If the custom server’s version id is lower than this, this structure is returned without this field.

DT_MSG_INFO_ST