In version 7.6, Spotfire introduced Values axis values.  You will see it in places like the Color by selector or when creating rules in the Show/Hide Items menu (part of each visualization's Properties dialog).  Examples are shown below in the screen shots.


Values axis values connects a visualization property to the values axis of the visualization so that if what is on the values axis changes, the user doesn't also have to change the color by or Show/Hide.  Values axis values connects them. 

In the example shown below, gas production is on the y axis.  The color by is set to Values axis values and the Show/Hide rule is set to Values axis values.  The visualization colors by the min and max of Gas Production (because that is what is on the values axis or y axis).  In the second screenshot below, I have changed the y axis to be Gas Production, but because Color by and Show/Hide were connected to Values axis values, rather than Gas Production, they do not require updating.  They update with the change in the y axis.