This is the low left position in world space of the chart that is appointed via premadeChartThatIsRotationPivot (which by default is the first chart: premadeChart0). All other premade charts will automatically be positioned beside this chart, unless their positions has been explictily set via chart.Position_worldspace(todo link). If you want a premade chart for which you have explicitly set the Position to revert back to the auto-positioning layout you can use RevertPremadeChartsToAutomaticPositionLayout. "positionOfPremadeCharts" changes only the worldspace position of the premade charts. The screenspace position can be changed independently and is not tied to the automatic layouting.