Possible? Macro broadcast for each slave to select a different target?

[envio11]

On my team of mages I use Focus for Polymorph - Every one has his own target/focus key

Focus:


Polymorph:


And small video
https://youtu.be/XPrjPkBegZk

could you explain how does this focus macro works?? before engaging you manually select the mob you want to be polymorphed by mage-1 click focus macro and he "remembmers" the target right? and do this with each one?