The following methods control the display and spacing of grid lines in the viewports.
Returns the spacing between grid lines in units.
Returns the number of grid lines between major grid lines.
The following 3ds Max system global variable is associated with the Viewport grids:
Contains the currently active grid. If the home grid is active, returns the value undefined. You can assign a grid node object to this variable to make it the currently active grid.
You can also return to the home grid by setting activegrid = undefined.