Dialogue Portion The dialogue portion of the message is optional and is used to convey information about a dialogue between nodes at the component sublayer | Dialogue Portion The dialogue portion of the message is optional and is used to convey information about a dialogue between nodes at the component sublayer. It establishes a flow of information within a particular context for a transaction. Information such as the protocol version and application context is used to ensure that two nodes interpret the component sublayer s contents in the same manner using an agreed upon set of element definitions. ITU Dialogue There are two categories of dialogues structured and unstructured. An unstructured dialogue is one in which no reply is expected. This type of dialogue uses a Unidirectional message type at the transaction layer. A structured dialogue requires a reply. Within these two general categories of dialogues dialogue-control Application Protocol Data Units APDU are used to convey dialogue information between TC-Users. The following are four types of APDU Dialogue Request Dialogue Response Dialogue Abort Dialogue Unidirectional Following is a description of each of these APDU and the information elements contained therein. The ITU unstructured dialogue uses the following dialoguecontrol APDU Unidirectional Dialogue The Unidirectional Dialogue consists of an Application Context Name and optional Protocol Version and User Information. It is used to convey dialogue information in one direction for which no reply is expected. The structured dialogue uses the following dialogue-control APDUs Dialogue Request The Dialogue Request consists of an Application Context Name and optionally Protocol Version and User Information. It is used to request dialogue information from another node such as the context between the nodes what set of operations will be included and to distinguish that the correct protocol version is being used to interpret the information that is being sent. Dialogue Response The Dialogue Response is sent as a reply to a Dialogue Request. In addition to the information elements of the Dialogue Request it .
