Invalidation Level
An invalidation level is the price where your wave count dies. It is not a suggestion. It is a hard line. If price crosses it, your analysis is wrong and you need a new count. The most common invalidation level comes from the rule that Wave 4 cannot enter Wave 1 territory in an impulse. So if you label something as Wave 4, the top of Wave 1 is your invalidation level. Professional analysts always mark these on their charts before entering a trade. This is what separates Elliott Wave from vague pattern recognition. You have a built-in stop loss from the theory itself. Every wave count should have an invalidation level. If it does not, the analysis is incomplete. Treat it as your risk management anchor.
You count EUR/USD with Wave 1 topping at 1.0950 and Wave 3 topping at 1.1200. You believe Wave 4 is underway. Your invalidation level is 1.0950 because Wave 4 cannot overlap Wave 1. If price drops to 1.0940, your impulse count is dead. You either re-label the structure as a diagonal or consider an entirely different count. A trader might place a stop just below 1.0950 to protect the position with a defined risk.