Durability is one of the four core stats to a character's ability, along with strength, speed, destructive ability and power. It is measured by the amount of energy a character is capable of surviving without being incapacitated for any significant period of time. Scale wise, regular durability is listed with the exact same units strength is listed with. However, unlike strength durability can be divided up into several categories. The main three categories being Blunt Durability, Piercing Durability and Heat Durability. Although depending on a character's abilities they may qualify for additional categories.
This is what is most often referred to when talking about durability, and as such it is treated as the standard kind. Blunt durability is used to measure the amount of energy a character can survive from non-sharp objects. Examples of this would be punches, kicks, explosions and clubs. This is the default durability listed on pages, with the other two kinds being optional additions.
Piercing durability is the amount of pressure a character can take without being impaled. As the description suggests, piercing durability is most often measured in pressure, specifically pascals. A feat is viable as an example of piercing durability when a sharp object fails to produce any more than a shallow cut on a character. Any more and the feat is treated as an example of the limits of a character's piercing resistance.
Heat durability, also known as heat resistance, is a measure of how much heat a character can survive without serious damage. It is measured in terms of Celsius, rather than energy or pressure. It should be noted that, unlike the other kinds of durability, heat durability can also be listed in terms of how little heat a character can tolerate, such as surviving arctic waters with no lasting harm.