In Grapher you can break an axis and use a specific symbol on both the plot and the axis itself to indicate where the break is. This is a available for any plots where Break Axis is enabled. 

To break the axis and change the symbol properties:

1. In the Object Manager, click the desired axis to select it.
2. In the Property Manager, click on the Break Axis tab.
3. In the Break Axis section, check the box next to Break axis box to break the axis.
4. Choose which data interval you would like to be skipped in the graph by entering axis values into the Break from and Break to fields.
5. In the Break mark properties section, choose the desired axis break symbol from the Type field. 
6. Choose the desired plot break symbol from the Break plot with field.
   • Use Symbol to manually choose a specific symbol to use in the Plot break symbol section.
   • Use Axis break mark to use the same symbol as the axis break symbol. 
   • Use Grid line to draw a grid lines at the start and end of the break.
   • Use None to leave an empty gap at the break.

Show an axis break with empty space (upper left), a user-defined symbol (upper right), the break axis symbol (lower left), or grid lines (lower right).

Updated March 10, 2020