Adding "Levels" to a Custom Indicator

[Forex Trader]

Is it possible to write a Custom Indicator wherein "Levels" are predefined so I dont have to input them everytime I attach the Indicator to the chart.

[Forex Trader]

Of course. See example "MQL4: Williams Percent Range, %R"

#property indicator_level1 -20
#property indicator_level2 -80