Workout: fixed power values

I want to create a workout: A step test that starts at 150W and increases the power with 25W every 90 seconds.

The problem is that when your FTP changes, the power of these steps changes accordingly. But that should not happen: This workout is meant to measure your Peak Power Output (and deduce from that your FTP). So, the power should be really a fixed value, independent from your FTP.

What I have to do now when I want to do this workout is set my FTP to 200 (which I had set during definition of this workout), do the workout, and then not to forget to reset my FTP to my real value.

So, the requested feature is: Be able to indicate when defining a workout whether the power values should be relative to your FTP, or whether they should be absolute values.