Each Bluetooth device has a device class (type of device and services it provides) which is part of the responds to an inquiry. The device class has a total length of 24 bits and is separated in three parts. First there is the Service Class which is a bit field (first 11 bits) and second and third are the Major (5 bits) and Minor (6 bits) device class. The last two bits indicate the format. Not all possible values will be described here, you can find the complete specification here.