What component makes an AMI message character-based?

The core reason for identifying that an AMI message is character-based lies in the definition of what constitutes a character within the context of computer systems. A character-based message is fundamentally composed of characters, which can include letters, digits, punctuation, and other symbols that are part of a text encoding system. This composition enables the message to be human-readable and easily processed by applications designed to interpret such text.

In the context of AMI, which handles a variety of message formats for financial transactions and communications, messages that are character-based facilitate easier debugging, logging, and processing because they can be directly viewed and understood. This is essential for clear communication between different systems and parties involved in financial transactions.

Other options do not define what makes a message character-based; rather, they pertain to formats or elements that may not directly relate to the character nature of the message. Numerical data, graphics, and binary encoding represent different forms of data representation that do not align with the concept of being purely character-based. Therefore, the defining trait of an AMI message being character-based is indeed its composition of characters.