Old / new BT module communication:
The old / new BT module do have a sligthly different command set. To keep them compatible a function has been added which returns, based on the HW identification, the command string which matches to the module. In case a command is not supported the value 0 is returned and the calling function may react. E.g. with skipping of configuration steps like it is done now for the new module.
6 It helps development, allow smalled upgrades, and improve security as a bad manipulation won't kill the bootloader, responsible fot the next firmware upgrade.