That functionality doesn’t exist anymore as far as I know, it went the way of click macros and smart heal
macros, you used to be able to target unit frames by modifiers back in vannila, same way as you could use decursive or spam a macro that would heal anyone below 70% hp with a lower rank heal, and below 50% with a max rank heal all while not actually having to pick someone. The macro would just search for the person closest to you with low Hp