The Murrey Math Line X Indicator is a popular and free forex indicator for MT4 platforms. The indicator is based on the Murrey Math trading system, which is a technical analysis system that uses nine lines to plot support and resistance points. The indicator works by plotting the nine lines on the chart, which are then used to identify potential areas of support and resistance. The indicator is also useful for identifying potential trend changes, as well as for identifying potential areas of support and resistance.