The EN13537 test involves a heated mannequin, a sleeping bag, a sleeping mat, a few other bits, controlled conditions and a scientist. It aims to simulate an actual person sleeping in a bag, where the bag is the only variable. There are 3 figures that drop out of this test. Here, word for word are the precise definitions as per the EN 13537 standard. We urge you to read between the lines, the language used is precise and has been very carefully chosen.
Comfort Temperature (T comf)
Lower limit of the comfort range down to which a sleeping bag user with a relaxed posture such as lying on their back is globally in thermal equilibrium and just not feeling cold (related to standard woman and in standard conditions of use).
Limit Temperature (T lim)
Lower limit at which a sleeping bag user with a curled up body posture is globally in thermal equilibrium and just not feeling cold (related to standard man and in standard conditions of use).
Extreme Temperature (T ext)
Lower extreme temperature where the risk of health damage by hypothermia occurs (related to a standard woman and in standard conditions of use).
To do the topic justice it requires further reading, but just like when you click that 'I have read the terms and conditions' tick box before you upgrade your phone we can rarely be bothered. The topic is long, hotly debated and long so we have left that for another page.