USDX is a custom MT4/MT5 indicator coded by EarnForex.com. The indicator is based on the formula for the ICE's dollar index. It requires the following currency pairs to work: EUR/USD, USD/JPY, GBP/USD, USD/CAD, USD/CHF, and USD/SEK.
The MT4 version displays the indicator as a line (you choose which price type to use for the line; the default one is Close). The MT5 version displays the indicator as Japanese candlesticks. Both versions can apply moving averages to the display.
More information about this custom MetaTrader indicator is available here: https://www.earnforex.com/metatrader-indicators/USDX/
Any contributions to the code are welcome!