Welcome to today's lesson on finance related terms. Today, we will be discussing the new PREV constant, available in the Indicator Builder. This constant is commonly used in custom indicators to reference the previous output of the same formula. Let's look at a general example: PREV+1. This formula takes the previous result and adds one to it. It is "primed" with the first output, allowing for continuous calculation. The PREV function is particularly useful for exponential calculations, such as an 18% exponential moving average: (close * 0.18) + (PREV * 0.82). This formula takes 18% of the closing price and adds on 82% of the previous result. For more information, search for 'Prev Constant' in the MetaStock 6.0 online help or User's Guide index.