These indicators describe the behavior of a Weibull distribution, and are analog to shape and scale factors.

The m indicator (the median) corresponds to the point in time where reliability is at 50% becoming an easy to locate measure of central tendency, based on the data or office automation tools available.

The R2m indicator corresponds to the reliability after 0.5 from the median, i.e., the probability value on the reliability curve of m plus 50% of itself.