Default messages are useful for gracefully handling unrecognized messages. When an unrecognized message arrives, your interface (or Iguana) will ACKnowledge the unexpected message and then log it for future investigation by an administrator.

By defining a default message, this means that all unexpected incoming messages are still processed and the desired fields are extracted from the MSH segment. In the Message Grammar of a default message, three items are apparent:

• The segment grammar contains only the MSH segment;
• The table grammar is blank; and
• The Ignore Segments not in grammar option is turned on.

This means that no data is mapped out of the message, only the MSH segment is parsed and all other segments will be ignored.

	Since a default message is designed to match all unexpected messages, the matching rules specified in the Identity window do not apply.

In Chameleon there are two ways to define default messages: