Minor Gridline Properties Dialog Box, Visibility
Select Visibility on the Minor Gridline Properties dialog box to set visibility options for minor gridlines in the chart.
Select an option to indicate how the report item is initially displayed in the report.
Select this option to show the report item.
Select this option to hide the report item.
Select this option to vary the initial visibility using an expression.
Type an expression that evaluates to a Boolean value of True to hide the item or False to show the item. Click the Expression (fx) button to edit the expression.