>From the ANSI standard:
This protocol describes the behavior of instances of class Error. These are used to represent error conditions that prevent the normal continuation of processing. Actual error exceptions used by an application may be subclasses of this class.
As Error is explicitly specified to be subclassable, conforming implementations must implement its behavior in a non-fragile manner.

Additional notes:
Error>defaultAction uses an explicit test for the presence of the Debugger class to decide whether or not it is in development mode. In the future, TFEI hopes to enhance the semantics of #defaultAction to improve support for pluggable default handlers.

	private
	devDefaultAction isDevelopmentEnvironmentPresent runtimeDefaultAction

	exceptionDescription	top
	defaultAction The current computation is terminated. The cause of the error should be logged or reported to the user. If the program is operating in an interactive debugging environment the computation should be suspended and the debugger activated.

	private	top
	devDefaultAction
	isDevelopmentEnvironmentPresent
	runtimeDefaultAction Dump the stack trace to a log file, then exit the program (image).