The aim is to define kind of "step groups"
Step 1 - 0 actionA
Step 2 - 0 actionB
Step 3 - 0 actionC

This will:
Inmediately --> actionA
stepdurantion after --> actionA + actionB
stepduration after --> actionA + actionB + actionC
from now on all 3 actions will execute

If we can define an interval

Step 1 - 0  /3  actionA
Step 2 - 0  /3  actionB
Step 3 - 0  /3  actionC

Inmediately --> actionA
stepdurantion after --> actionB
stepduration after --> actionC
form now on, the same sequence wll be executed