The firmware built using the Firmware Development Kit supports an additional descriptor, the ZTEX descriptor 1. This descriptor identifies the device and firmware, provides compatibility information (e.g. to avoid that a device is loaded with the wrong firmware) and specifies the communication protocol. A description of the descriptor is given in ZtexDevice1.
The communication protocol defines how the functions provided by the firmware can be accessed. Currently there is only one protocol implemented, the so called interface 1. A description of the interface is given in Ztex1v1.