Thanks for your feedback! This is on my to-do list of things to fix-- some of the flavors have been developed using monthly returns and some use annual. In both cases the x axis is variance of the periodic returns. Also in some cases the returns are log returns which is also a todo. I will fix it so that the x axis is labeled with the user's choice of risk metric used by the optimizer. Also, I should have mentioned it, but the risk choice isn't implemented in the backend yet so the risk metric choice just defaults to variance for right now.