Is the statement "fields are defined in message structure" true or false?

The statement "fields are defined in message structure" is indeed true. In the context of the Avaloq Message Interface (AMI), a message structure specifies the organization and layout of data within a message. This includes defining various fields that represent specific pieces of information and establishing their respective data types, constraints, and relationships.

Fields are integral components of the message structure, allowing different systems to communicate effectively by following a defined protocol. These fields can include elements like identifiers, dates, amounts, and textual descriptions that are essential for the message's purpose. Thus, the assertion correctly reflects the foundational principles of how messages are structured within this framework.

The other options do not accurately represent the relationship between fields and the message structure, which is clearly defined and systematic in the AMI architecture.