What aspect does the source Network NOT define?

The aspect that the source Network does not define is the message structure. In the context of the Avaloq Message Interface, the source Network primarily focuses on the delivery mechanisms and how messages are transmitted between systems. This includes specifying the delivery type, channels, and the network header that facilitates the sending of messages.

However, message structure refers to the content and organization of the data within the message itself, which is defined independently of the network layer. The message structure is concerned with how information is formatted and coded, including elements like fields and data types, which are part of the application layer rather than the network layer. Thus, while the network plays a crucial role in the transfer of messages, it does not dictate how those messages are structured internally.