Example of using IndicatorSetDouble() function. This is an indicator that turns upside down the maximum and minimum values ​​of the indicator window and values ​​of levels, on which the horizontal lines are placed.

The indicator is created in a separate window, and three horizontal lines on levels 25, 50 and 75 are also added in the same window:

//--- display three horizontal levels in a separate indicator window
#property indicator_level1 25
#property indicator_level2 50
#property indicator_level3 75

Then, a signature is placed in OnInit() function for each level:

//--- set descriptions for the horizontal levels 
   IndicatorSetString(INDICATOR_LEVELTEXT,0,"First Level (index 0)");
   IndicatorSetString(INDICATOR_LEVELTEXT,1,"Second Level (index 1)");
   IndicatorSetString(INDICATOR_LEVELTEXT,2,"Third Level (index 2)");

Arrived ticks are calculated during the indicator operation in tick_counter variable. The indicator window rendering changes each 10 ticks - the minimum value is changed from 0 to -100, while the maximum one - from 100 to 0. Thus, the indicator is "reversed".