What is a Secondary Indicator?
The functionality of the primary indicator and secondary indicator are exactly the same. The purpose is to give you a long or short trend signal.
The combination of the primary and secondary indicators work together to try and match up and signal at the best possible moment to enter a trade.
When you are on your hunt for the secondary indicator you need to look for an indicator which is completely different than your primary indicator when it comes to providing signals.
This is because if you match an indicator that give practically the same signals at the primary indicator there is no purpose to having two different indicators.