Lorna Mitchell has a tip for those using the Google Charts API to plot the data from their applications - a simple way to add multiple axis labels to the chart's output.

The axes in Google Charts are a bit interesting, because what they display bears absolutely no resemblance to what data is there - you label the axes separately, even if they are numbers. To label multiple things - in this example a scale and some units, you simply specify the axis more than once.

In her example it creates a bar graph that puts the values for "chxr" and "chxl" on the axis. The Google Charts API can be used to generate other sorts of dynamic graphs too including the traditional pie, line or scatter charts. It can also create things like QR codes and formula images, all on the fly.