Differences between the use of block or function for the implementation of temperature, density... functions

Discussion started during Devcom6 (during Jean-Louis' presentation). Why has it been done like this and what would it changed ?

Because functions are used, inner and outer apparently can't be used in this case inside functions.

Because functions are used, it is not possible to redeclare a package inside it, for instance for CoolProp mediums #32.