DescriptionSets or returns the major increment of the axis, the increment between its major gridlines and/or major ticks marks.
When creating a new chart, or reading a chart in from a file where the major increment value is not specified, the major increment value is automatic, which is represented with -1.
This property can be set to any value greater than or equal to zero. If you set this to a negative value, it will set the major increment of the axis to auto.
If ValueAxis.UseLogarithmicScale is turned on, then this property represent the power of the major unit in base 10 (or whatever base you've manually set). For instance, if this value is set to 2. Then with UseLogarithmicScale turned off, the resulting file will have a major unit of 2. If UseLogarithmicScale is turned on, then the resulting file will have a major unit of 100 (10 2).