Accessing a Second Dataseries as an input parameter

[SigLogic]

I am developing an indicator that will compare a value to a second instruments dataseries. Would anyone know how I can convert the string parameter to a dataseries?

For example if string parameter (parameter name= input_instrument, value = SPY)

Any help would be greatly appreciated.

[NinjaTrader_Bertrand]

SigLogic, you would simply make a public string input in your script, the Add() method in Initialize() would take the instrument name as string parameter per default.