def tcl_prep_otaver(ota=None):
    """
    Prepare variables for OTA versus full check.

    :param ota: The starting version if OTA, None if not. Default is None.
    :type ota: str
    """
    if ota is not None:
        mode = 2
        fvver = ota
    else:
        mode = 4
        fvver = "AAA000"
    return mode, fvver