This is a function contained within the Kernel Gridding window.
With Auto On active, changing a value for on of the grid geometry variables (grid length, spacing, or lines) results in changes to the other two parameters, maintaining the relationship: [lines-1]*[spacing] = grid length.
With Auto On inactive, the grid length, spacing, or lines can be changed independently of one another. You may make entries for all variables if you like.
Or, enter a change of values for one variable and then click on a the button for one of the other variables. The variable you click will be recalculated to match your manually enter specification.
If you make a change without updating all parameters, you will receive a message on an attempt to Execute: "Grid numbers do not match"
What do you want to do?