E.g source code of standard RSI indicator which comes with TS installation:
inputs:
Price( Close ),
Length( 14 ),
OverSold( 30 ),
OverBought( 70 ),
OverSColor( Cyan ),
OverBColor( Red ) ;
variables:
RSIValue( 0 ) ;
RSIValue = RSI( Price, Length ) ;
Plot1( RSIValue, "RSI" ) ...