What Does Incline Mean on Ellipticals?

What does the incline number on the fitness equipment mean? Is it the equivalent of incline grade on the road?

In general, ellipticals offer incline levels anywhere from 0 to 20. The higher the incline, the more challenging your workout will be. When your elliptical is set to the higher levels, you'll be engaging different lower body muscles than you would at the lower incline levels. This allows you to mix up your routine and challenge different muscle groups. 

The gradient or grade equating to incline percentages is a measurement of the height distance for every 100-horizontal distance. e.g. A one-in-100 gradient = 1%, and a rise of 15 meters for every 100 meters is a 15% grade. 

You may use trigonometry to measure the gradient L = √ (D2 - H2)