TFT custom script?

There's a new action in TFT called custom script. Ne body know what it does? Thanks.

well u can use this to execute jass code.
If u put some function in the first section of the trigger u can call it from that action or u can use it to execute something else like.
set udg_test=1000.
If u ever used dkslayers dialog engine which u had to put first on your map. This new feature in the we lets u put functions first in your map and the call them from wherever u want.