188 ◾ Software Metrics
is notion of soware error is also highly relevant for soware fault
tolerance, which is concerned with how to prevent failures in the pres-
ence of soware errors. If an error state is detected and countered before
it propagates to the output, the failure can be prevented. Preventing error
states from propagating is the goal of soware fault tolerance. Researchers
continue to search for methods that enable soware to operate dependably
even when it contains faults that have been triggered. Soware errors do
not necessarily cause failures in fault-tolerant soware.
Unfortunately, the terminology used to describe soware problems
is not uniform. If an organization measures soware quality in terms of
faults per t