Editing Spiral model (section)

===Perform four basic activities in every cycle===
This invariant identifies the four activities that must occur in each cycle of the spiral model:
# Consider the win conditions of all success-critical stakeholders.
# Identify and evaluate alternative approaches for satisfying the win conditions.
# Identify and resolve risks that stem from the selected approach(es).
# Obtain approval from all success-critical stakeholders, plus commitment to pursue the next cycle.
Project cycles that omit or shortchange any of these activities risk wasting effort by pursuing options that are unacceptable to key stakeholders, or are too risky.

Some "hazardous spiral look-alike" processes violate this invariant by excluding key stakeholders from certain sequential phases or cycles. For example, system maintainers and administrators might not be invited to participate in definition and development of the system. As a result, the system is at risk of failing to satisfy their win conditions.