Rejuvenation on party with 1 macro

[Iceorbz]

I was hoping wowphreak had shown me a very neat trick...

Today, I learnt we can go:
/castsequence reset=target Hunter's Mark, Null

Instead of:
/castsequence reset=target Hunter's Mark,,, (comma's to 255 limit).

After boxing more then a year now, there's still a lot to learn.
The community rocks.

Does null mean it wont do it again, till another target is chosen?