MajorUnitIsAuto Property
True if Microsoft Excel calculates the major units for the axis. Read/write Boolean.
Remarks
Setting the MajorUnit property sets this property to False.
Example
This example automatically sets the major and minor units for the value axis in Chart1.
With Charts("Chart1").Axes(xlValue)
.MajorUnitIsAuto = True
.MinorUnitIsAuto = True
End With