Lowest Value but for an indicator

Hello,

How can I use the same logic I use for finding the lowest low value for the price but applied to the AO indicator? What I want is to find the lowest low value of the AO in a given period. For price value I use:
AO_Lowest_Value = Low[Lowest(NULL, 0, MODE_LOW, bar_count, 0)];

Also if I have a time value of a given bar, how can I know it's bar index number using the time value for that bar (since it's unique for each bar) on a given chart at any time?

Thank you.
Cleon
And after this:

AO_Lowest_Value = Low[Lowest(NULL, 0, MODE_LOW, bar_count, 0)];

How can i know what bar is that ?

Thank you.
Cleon
Anyone?
cleon:
Anyone?
Use help, F1. It is quite obvious.
ArrayMinimum function
Thank you Stringo.