This indicator implements the original "Average True Range (ATR)" developed by John Welles Wilder Jr., as described in his book—New Concepts in Technical Trading Systems [1978].

It uses Wilder's moving average, also known as the smoothed moving average (SMMA), instead of a simple moving average (SMA) as used on MetaTrader's built-in ATR indicator. The default period applied is 7, instead of 14, as per the description in his book.

The code uses conditional compilation and will compile on both MQL4 and MQL5. Please note that all my CodeBase publications' source code are now also available in "Public Projects" tab of MetaEditor under the name "FMIC".