Extreme: Lower extreme temperature where the risk of health damage by hypothermia occurs not feeling cold (related to standard man and in standard conditions of use).
Limit: Lower limit of which a sleeping bag user with a rolled-up body posture is globally in thermal equilibrium and just not feeling cold (related to standard man and in standard conditions of use).
Comfort: Lower limit of the comfort range down to which a sleeping bag user with a relaxed posture such as lying on the back is globally in equilibrium an just not feeling cold (related to standard woman and in standard condition of use).