2DAMEMORY1 is a memory token, storing a a row ID number. You can have as many as you want. I assume in this case you will only need the one, but it could be 2DAMEMORY2, 2DAMEMORY3, etc. depending on how many rows you needed to add. So, for example, you could have a scenario where you added say three tracks to the 2DA, and created three separate scripts, one for each track. Each script would use a different memory token, to match the specific track.