Could someone please explain to me what this value does/means?
Thanks
iBullsPower(NULL, 0, 13,PRICE_CLOSE,0);

Looking for what 'int period' (third value) means, what a value of 13 or if I change to 20 is telling me or doing for me in an EA or Indicator? is 'int period' TF specific?

I'm using Null, then 0 - for any TF, 13 - not sure what this does, PC - I think most use 6 (Weighted close price, (high+low+close+close)/4) and 0 at the end.

I was told to do an optimization but don't know how.

Thanks