How is the appearance datatype used in BLE adverts?

The GAP service supports an appearance characteristic which is a 16 bit value used to associate the device with a generic category. For example, the appearance characteristic could be set as generic phone, thermometer or bar code scanner. A complete list of possible GAP appearance values can be found on the Bluetooth website under assigned numbers. This appearance information can also be made available in an advert using the appearance data type (0x19) so that a central device can display an icon representing the the generic device type of the peripheral device.