And that's why it's an external property. So because enthalpy is a man made concept, we can't talk about absolute values of enthalpy. They simply do not exist. What we do talk about are changes in enthalpy. And in order for changes in enthalpy to exist, we must assign zero values to Cherton atoms with the churchin's elements, okay? And in fact, under a standard state of 1 bar or 750 tor and a certain temperature such as 25 degrees Celsius, all elements such as diatomic, hydrogen diatomic, oxygen, carbon diatonic, fluorine and so on are assigned a value of zero entropy, zero joules per mole.