Characteristics are the lowest and the most important echelon of the Bluetooth Low Energy technology. Encapsulated by a related service, these are the actual state variables, each of which stores a single piece of relevant measurement and information data:
Figure 14: Relationship of Characteristics, Service, and Profile
Just like services, these have a UUID, which can be 16-bit or 128-bit based, depending on whether a characteristic has a standard or custom definition. For example, the blood glucose measurement characteristic has a UUID of 0x2A35. Also, just like services, a manufacturer is free to define custom characteristics ...
