About how often do your severe headaches occur:NRat:Pt:^Patient:Qn:PhenX
about how often do your severe headaches occur:nrat:pt:^patient:qn:phenx
About how often do your severe headaches occur:Number=Count/Time:To identify measures at a point in time:^Patient:Quantitative:PhenX
about how often do your severe headaches occur:number=count/time:to identify measures at a point in time:^patient:quantitative:phenx