Recording menstruation data in Apple Health app

If I am not bleeding and it is not an expected period day, should I be logging “no flow” for my period or should I leave that day blank (for flow)? I’m not sure if logging “no flow” indicates that I’m expecting to be bleeding while I am on my period but am not bleeding. The only reason I ask is because I don’t know if logging “no flow” on a non-period day is going to make the algorithm think that it IS a period day, I just didn’t bleed, and then skew the data.