Filter by current active stock industry (amibroker)

Hi expert, I have an afl and would like to filter by the industry of the current active stock, how could I write this?

Filter = industryID() = industryid(0);

But it returns all the stocks to me, didn't filter by the current industry of the stock in the active chart.

Please help. Many thanks.

hi i am new to this group.
i am interested in knowing about stock filtering (all 2000+ stocks in nse)
particularly 2 to 3 days down stocks with minimum trading volume of 5,00,000+
can anyone help me in this.

One line

Filter = Ref( Sum( C < O, 3 ), -1 ) == 3 AND V >= 500000;

thx a lot

i am new to this amibroker.
where to write these type of codes and what is the result.
can somebody help me in understanding small tricks in ami broker filters