cam belt AUDI A4 2018 Owners Manual
[x] Cancel search | Manufacturer: AUDI, Model Year: 2018, Model line: A4, Model: AUDI A4 2018Pages: 403, PDF Size: 66.81 MB
Page 122 of 403

Assistance systems
This message appears if you would like to switch
the system on and there is a stationary object di
rectly in front of your veh icle.
Door open
The system is not ava ilable when the door is
open.
Audi pre sense
Introduction
A pp lies to: ve hicles w ith Audi p re se nse
W ithin the limits of the system, the pre sense
functions can initiate measures in particularly
dangerous situations to protect the veh icle pas
sengers and other road users .
- Due to the interlinking of various vehicle sys
tems, crit ical dr iving s ituations can be detected
by
pre sense basic and measures for preventa
tive occupant protection are can be initiated .
- The
pre sense front system uses the data from
the adapt ive cruise control* radar sensors and
the camera to calculate the probab ility of a col
li sion. Withi n the limits of the system, an im
pending collision with vehicles can be dete cted
in both urban and rural speed ranges. In this
case, the system warns the driver visually,
acoustically and with a jerk on the brakes if nec
essary. If needed, it can initiate a partial or full
deceleration to reduce the co llision speed or to
avo id the collision under certain c ircumstances .
In conjunct ion with pre sense basic/rear, the
front safety belts are also revers ibly tensioned
when needed . The pre sense front is also active
whe n adapt ive cruise control* is swit ched off.
- Pre sense rear contains pre sense basic func
tions. It uses the data from the side assist* ra
dar sensors and calculates within the limits of
the system the probab ility of a rear end coll i
s ion with the vehicle behind you. Pre sense rear
is also active when side assist* is switched off.
- Within the limits of the system,
pre sense city
uses the camera data and can detect an im
pending collision with vehicles and pedestrians.
In this case, the system warns the driver visual
ly, acoustically and with a jerk on the brakes if
necessary. If needed, it can initiate a full decel
eration to reduce the collision speed or to avoid
120
the collision under certa in circumstances . In
conjunction with pre sense basic/rear, the front
safety belts are also reversibly tensioned when
needed .
A WARNING
-
Read the general information inc> & in Gen-
eral information on page 109,
c> & in Gener
al information on page 130.
(D Tips
- Certain pre sense funct ions sw itch off when
dr iving in reverse.
- The pre sense functions may not be availa
ble if there is a malfunct ion in the ESC sys
tem or the a irbag control module.
- Note that the reversible belt tensioner on
the front passenger's side deactivates when
the front passenger's airbag is deactivated .
- Switch the pre sense off when you are not
using public streets or when loading the ve
hicle onto a vehicle carrier, tra in, sh ip or
other type of transportation. This can pre
vent an undesired intervention from
the pre
sense system.
Audi pre sense basic
Description
App lies to : vehicles wi th Audi pre sense basic
The pre sense bas ic functions are activated at a
speed of approx imately 20 mph (30 km/h) or
higher .
The following functions can be triggered under certain condit ions w ith in the lim its of the sys
tem:
- Tensioning of the safety belts (for examp le,
during heavy brak ing): the front safety belts
have reversib le be lt tens ioners. If a collision
does not occur, the safety belts loosen slightly
and are ready to trigger again.
- Closing the windows and sunroof* .
-
Page 124 of 403

Ass is tan ce sys tems
your steering whee l ang le as long as you are ac
tively steering. Evasive steering support is availa
b le at speeds between approximately 20 mph
(30 km/h) and 90 mph (150 km/h).
Tu rn assist
When start ing to drive and up to speeds of maxi
mum
6 mph (10 km/h), the turn assist uses a
braking intervention to prevent your vehicle from
colliding with an oncoming vehicle when turning
left or right (available in certain countries). The
braking intervent ion causes your vehicle to stay
in its lane.
A WARNING
-Pre sense front cannot overcome the laws of
physics.
It is a system des igned to assist and
it cannot prevent a collision in every circum
stance. The driver must always i ntervene.
T he driver is always responsib le for braking
at the correct time. Do not let the increased
safety provided tempt you into taking risks .
This could increase your risk of a collision.
- The system can deploy incorrectly due to
system-specific limits .
- Please note that the sensors and the camera
do not always detect all objects or lane
markings. This increases the risk of an acci
dent.
- Pre sense front does not react to people, an
imals or ob jects that are crossing the veh i
cle's path or that are difficu lt to
detect¢ .&.
in General information on page 109.
-Reflective objects such as guard rails or the
entrance to a tunnel, heavy rain and ice can
affect the fu nction of the radar sensors and
the system's ability to detect a coll is ion risk .
(D Note
The sensors can be displaced by impacts or
damage to the bumper, whee l housing and
underbody. Pre sense front can be impa ired
by this. Have an authorized Aud i dealer or au
thorized Audi Service Fac ility check their func
tion.
l ) Th is is not availab le in some countr ies.
122
(D Tips
- You can cancel the braking with increas ing
force that is initiated by the system by bra k
ing yourself, by acce lerating not iceably or
by swerving.
- Keep in mind that pre sense front can brake
unexpectedly. Always secure any cargo or
objects that you are transporting to reduce
the risk of damage or injury.
- Specific pre sense front functions switch off
when the ESC is restricted or sw itched off
¢ page 147 or the hill ho ld assist" is
switched on
¢ page 148 .
Audi pre sense rear
Description
Applies to : vehicles wi th Aud i s ide ass ist
If the risk of a co llision with a vehicle ahead is de
tected, the follow ing funct ions can be triggered:
- Reversible tensioning of the front safety belts
at the corresponding speeds .
- Closing the windows
and sunroof*.
- Infla ting the side bo ls ters* on the seat back-
rest.
- Ac tivat ing the emergency flashers with in -
creased frequency
l l.
The message Audi pr e sense. ¢ page 121,
fig. 122
will warn you about the danger.
Audi drive select": the function is not active de
pending on the mode selected.
A WARNING
- To reduce the r isk of an accident, please
no te t hat the s ide assist* radar sensors do
no t always dete ct every object.
-
- Pre sense rear does not react to people, ani
mals or objects that a re c ross ing the vehi
cle 's path o r that are d ifficult to detec t.
- Ref lective objects such as gua rd ra ils, heavy
rain and i ce can impair the func tion of the
radar sensors an d the abili ty to detect a col
lision risk.
Page 125 of 403

a co .... N ,....
N .... 0 0
3 co
(D Note
The radar sensors can be displaced by impacts
or damage to the bumper, wheel housing and
underbody. Pre sense rear can be impaired by
this. Have an authorized Audi dealer or au
thorized Audi Service Facility check their func
tion .
(D Tips
-The pre sense rear functions switch off
when towing a trailer .
- The pre sense rear functions may also
switch off if there is a malfunction in the
side assist* system.
Audi pre sense city
Description
Applies to: vehicles with Audi pre sense city
Within the limits of the system, pre sense city
can warn you of impending collisions with
vehicles and pedestrians and initiate the applica
ble braking maneuver if needed. Pre sense city is
active at speeds of approximately 6 mph (10 km/ h) and higher.
A pedestrian warning can occur at speeds up to
50 mph (85 km/h), and vehicle warnings can oc
cur at speeds up to 155 mph (250 km/h) . A pre
sense city braking maneuver is poss ible at speeds
up to 50 mph (85 km/h).
Warnings
Applies to: vehicles with Audi pre sense city
The system recognizes various dangerous s itua
tions. The
early warning occurs if:
- a vehicle driving ahead brakes suddenly,
- your own vehicle approaches a significantly
slower vehicle or stationary veh icle in the direc
t ion of travel.
- a pedestrian is standing in the lane or is moving
i nto the lane .
When this warning occurs, it may only be possi ble to avoid a collision by swerving or braking
strongly. The message
Audi pre sense .
Assistance systems
¢page 121, fig. 122 and a warning tone will
warn you about the danger.
Additionally, a jerk on the brakes may occur as an
acute warning when there is an imp ending colli
sion . If you do not react to the acute warning, pre
sense city can brake to the point of complete de
celeration within the limits of the system . T his
reduces the vehicle speed in the event of a colli
sion. The message
Audi pre sense . also ap
pears.
The following functions are triggered in conjunc
tion with pre sense basic/rear:
- Reversible tensioning of the front safety belts.
- Closing the windows and sunroof* .
- Inflating the side bolsters* on the seat back-
rest.
Audi drive select*: the function is not act ive de
pending on the mode selected.
A WARNING
- Pre sense city cannot overcome the laws of
physics.
It is a system designed to assist and
it cannot prevent a coll is ion in every circum
stance. The driver must always intervene.
The driver is always responsible for braking
at the correct time. Do not let the increased
safety provided tempt you into taking risks.
This could increase your risk of a collision.
- The system can dep loy incorrectly due to
system-specific limits.
- To reduce the risk of an accident, please
note that the camera does not always detect
every object.
- Pre sense city does not react to anima ls,
crossing or oncoming vehicles, objects such
as bars, railings or railcars, and objects that
are difficult to
detect ¢ A in General infor
mation on page 109 .
-In trailer mode, the braking behavior of the
tra iler can be d ifferent than usual during au
tomatic braking.
A WARNING
-Pre sense city may be restricted or not availa-
ble in the following example situations:
- in heavy fog, ra in, spray or snow
~
123
Page 126 of 403

Assistance systems
-when there are visual obstr uctions, such as
glare, reflections or variations in light
- when it is dark
- if the camera window or the windshie ld is
dirty, iced over, damaged or covered
- when driving on snow, ice or loose ground
- in curves
- if the ESC was restricted or switched off
- when towing a tra iler
- when the driver's seat belt is unfastened
- up to ten seconds after switching on the ig-
nition
(D Note
Impacts or damage to the camera mount on
the windshield can disp lace the sensor . Pre
sense city can be impa ired by this. Have an au
thorized Audi dealer or authorized Aud i Serv
ice Facility check the ir funct ion.
{D) Tips
- You can cancel the system braking interven
tion if you accelerate considerably or swerve
away.
- Keep in mind that pre sense city can brake
unexpectedly. Always secure any cargo or
objects that you are transport ing to reduce
the r isk of damage or injury.
- Specific pre sense city funct ions sw itch off
when the ESC is limited or switched
off
¢ page 147 or the hill descent assist* is
switched on
¢page 148.
-When there is a malfunction in the camera,
the pre sense city funct ions also switch off.
Settings in the
Infotainment system
A pp lies to: ve hicles w ith Audi p re se nse
.,. Select in the Infotainment system: IMENU I but
ton
> Vehicle > left control button > Driver as
sistance
> Audi pre sense.
Turn on/off Audi pre sense
-the pre sense func
tions can be turned on and
off.
124
If the system is switched off, it switches on again
automatica lly once the ignition is switched on
again.
Early warning -the early warning can be switch
ed
off or the pre sense city/front warning point
can be set
( Early /Medium /Late ).
Set the warning time for the early warning to
Early at first . If this causes undesi red early warn
ings to appear, then set the warning time to
Me
dium .
The Late warning time should only be set
i n spec ial circumstances, for example, when driv
i ng with a very dynamic style.
(D Tips
Your settings are automatically stored and as
signed to the remote control key being used.
Messages
Applies to: vehicles wi th Audi pre sense
II Audi pre sense: malfunction! Please contact
Service
This message appears when the pre sense func
tion is affected . For example, th is could be
ca used by a faulty sensor. Drive to an authorized
Audi dealer or authorized Audi Service Facility im mediately to have the malfunction corrected.
II Audi pre sense currently restricted . Restrict
ed sensor vision due to surroundings. See own
er 's manual
This message appears if the radar sensor and
camera view is obstructed, for example by leaves,
snow, heavy spray or dirt. If necessary, clean the
sensors and the area around the camera
¢ page 109, fig . 108 or ¢page 129, fig. 130 .
II Audi pre sense: currently restricted. Towing
mode
For vehicles wi th a trailer hitch installed at the
factory, the pre sense rear functions switch
off
when the electrical connector at the socket is
plugged in. There is no guarantee the functions
will switch
off when using a retrofitted trailer
hitch.
II Audi pre sense: currently restricted
Page 374 of 403

a co .... N ,....
N .... 0 0
3 co
Fuse panel © (brown)
4 Audi side assist
8 Smart module (tank)
11 12 Volt battery
12 Homelink
13 Rearview camera, peripheral cameras
14 Right tail lights
16 Right safety belt tensioner
Fuse panel © (red)
No . Equipment
2 Sound-amp
lifier
3 AdBlue heating
5 Trailer hitch (right light)
7 Trailer h
itch
8 Trailer hitch (left light)
9 Trailer h itch (socket)
10 Sport differential
11 AdBlue heating
Bulbs
Replacing light bulbs
For your safety, we recommend that you have
your authorized Audi dealer replace any bulbs for
you.
It is becoming increasingly more and more diffi
cult to replace vehicle light bulbs since in many
cases, other parts of the car must first be re moved before you are able to get to the bulb.
This applies especially to the light bulbs in the
front of your car which you can only reach
through the engine compartment.
Sheet metal and bulb holders can have sharp
edges that can cause serious cuts, parts must be
correctly taken apart and then properly put back
together to help prevent breakage of parts and
l ong term damage from water that can enter
housings that have not been properly resealed.
For your safety, we recommend that you have
your author ized Audi dealer replace any bulbs for
you, s ince your dealer has the proper tools, the
correct bulbs and the expert ise.
Fuses and bulbs
Gas discharge lamps (Xenon lights) :
Due to the high e lectr ical voltage, have the bulbs
replaced by a qualified technician. Headlights
with Xenon light are identified by the high volt
age sticker .
LED headlights*
LED headlights require no maintenance. Please
contact your authorized Audi dealer if a bulb
needs to be replaced .
.&, WARNING
Changing Xenon lamps without the necessary
equipment can cause serious personal injury.
- Bulbs are pressurized and can explode when
be ing changed. Potential risk of injury!
- On veh icles equipped with gas discharge
bu lbs (Xenon light) life-threatening injuries
can resu lt from improper handling of the
h ig h-vo ltage portions of such lamps!
- Only your authorized Audi dealer or quali
fied workshop should change the bulbs in
gas discharge lamps. There are parts with
sharp edges on the openings and on the
bulb holders that can cause serious cuts. If
you are uncertain about what to do, have the work performed by an authorized Audi
dealer or qualified workshop. Ser ious per
sonal injury may result from improperly per
formed work.
(D Tips
- If you st ill prefer to replace the light bulbs
yourself, be aware that the engine compart ment is a hazardous area to work
in¢ A in
Working in the engine compartment on
page 323.
- It is best to ask your authorized Audi dealer
whenever you want to change a bulb .
373
Page 396 of 403

Panorama glass roof. . . . . . . . . . . . . . . . . . . . 50
Emergency operation........... ..... .. 51
Parental control
DVD ... .. .. .. .. ........... .. .. .... . 239
Parking aid
Cleaning sensors/camera . . . . . . . . . . . . .
355
Parking brake
refer to Electromechanical parking brake . 88
Par king lights . . . . . . . . . . . . . . . . . . . . . . . . . 54
Parking location Audi connect vehicle control . . . . . . . . . . .
199
Parking system
refer to Parking systems ....... .. . 137, 138
Parking systems . . . . . . . . . . . . . . . . . . . . . . 136
Peripheral cameras . . . . . . . . . . . . . . . . . . 140
Rearview camera . . . . . . . . . . . . . . . . . . . .
138
Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Trai ler hitch . . . . . . . . . . . . . . . . . . . . . . . . 144
Particulate filter (diesel) . . . . . . . . . . . . . . .
322
Partition net . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Parts replacement . . . . . . . . . . . . . . . . . . . . 385
Pass-through . . . . . . . . . . . . . . . . . . . . . . . . . 73
PASSENGER AIR BAG light . . . . . . . . . . . . . . 283
Paths (Owner's Manual) . . . . . . . . . . . . . . . . 158
Pause (audio/video file) . . . . . . . . . . . . . . . . 236
Pedals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259
Peripheral display . . . . . . . . . . . . . . . . . . . . . 13 7
Personal route assistance . . . . . . . . . . . . . . 210
Phonebook
refer to Contacts . . . . . . . . . . . . . . . . . . . . 183
Physical princ iples of a frontal collision . . . 264
Picture format (video) . . . . . . . . . . . . . . . . .
239
Playback (media) . . . . . . . . . . . . . . . . . . . . . 236
Playlist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
Point of interest . . . . . . . . . . . . . . . . . . . . . . 207
Point of interest search . . . . . . . . . . . . . . . . 208
also refer to Point of interest . . . . . . . . . . 207
Polishing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 356
Pollutant filter (automatic A/C system) . . . . 76
Predictive efficiency assist . . . . . . . . . . . . . . 107
Pregnant women Special considerations when wearing a safe -
a ty belt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268 co .... ~ pre sense
:::l refer to Audi pre sense . . . . . . . . . . . . . . . 120 0
3 Presentation mode . . . . . . . . . . . . . . . . . . . . 213
co
Index
Presets list
refer to Favorites . . . . . . . . . . . . . . . . . . . . 225
Presets (radio) . . . . . . . . . . . . . . . . . . . . . . . 225
Pressure
Tire pressure monitoring system . . . . . . .
352
Prewarming . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Program guide
Radio .... .... .. .. ............... ..
223
Prompt
refer to Command (voice recognition sys -
tem) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
167
Proper occupant seating positions . . . . . . . 255
Proper safety be lt pos ition . . . . . . . . . . . . . . 267
Proper seating position
Front passenger . . . . . . . . . . . . . . . . . . . . .
256
Occupants . . . . . . . . . . . . . . . . . . . . . . . . . . 255
Rear passengers . . . . . . . . . . . . . . . . . . . . . 257
Protecting . . . . . . . . . . . . . . . . . . . . . . . . . . . 356
Q
quattro
Se lective wheel torque control ....... . .
Question 150
146
What happens to unbelted occupants?
264
R
Radio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
Additional station information . . . . . . . . . 224
Presets . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
Radio text . . . . . . . . . . . . . . . . . . . . . . . . . . 223
Station list . . . . . . . . . . . . . . . . . . . . . . . . . 222
Rain/l ight sensor
Headlights . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Interval mode (wipers) . . . . . . . . . . . . . . . . 60
Raising the vehicle . . . . . . . . . . . . . . . . . . . .
377
Random
refer to Shuffle . . . . . . . . . . . . . . . . . . . . . 239
Range (fue l level) . . . . . . . . . . . . . . . . . . . . . . 17
Reading lights . . . . . . . . . . . . . . . . . . . . . . . . . 5 7
Rear fog lights . . . . . . . . . . . . . . . . . . . . . . . . 54
Rear lid Escape latch . . . . . . . . . . . . . . . . . . . . . . . . .
46
also refer to Luggage compartment lid 43, 44
Rear Seat Entertainment preparation
refer to Audi Entertainment mobile . . . . . 235
395
Page 397 of 403

Index
Rearview camera
re fer to Parking systems . . . . . . . . . . 137, 138
Rear window defogger . . . . . . . . . . . . . . . . . . 78
Rear window sh ade . . . . . . . . . . . . . . . . . . . . .
60
Rear window washer system . . . . . . . . . . . . . 60
REAR (button) . . . . . . . . . . . . . . . . . . . . . . . . . 78
Recircu lation mode (automatic climate con-
t rol) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Recuperation . . . . . . . . . . . . . . . . . . . . . . . . . 17
Refueling ....... ........... ........ .. 317
Fuel filler door emergency release 319
Remote control
refer to Remote control key . . . . . . . . . . . . 38
Remote control key . . . . . . . . . . . . . . . . . . . . 38
Remote control operation Garage door opener (Homelink) . . . . . . . . . 52
Remote locking and unlocking
Audi connec t vehicle control . . . . . . . . . . . 199
Removing the caps (wheel bolts) . . . . . . . . . 363
Repair manuals . . . . . . . . . . . . . . . . . . . . . . . 383
Repairs Airbag system . . . . . . . . . . . . . . . . . . . . . . 286
Replacement key . . . . . . . . . . . . . . . . . . . . . . 38
Replacing Light bulbs . . . . . . . . . . . . . . . . . . . . . . . . . 373
Replacing wiper b lades . . . . . . . . . . . . . . 62, 63
Reporting Safety Defects . . . . . . . . . . . 261, 262
Reset
refer to Restart (MMI) . . . . . . . . . . . . . . . . 253
Reset button (trip odometer) . . . . . . . . . . . . 12
Resetting the trip odometer . . . . . . . . . . . . . 12
Residual heat (automatic climate control) . . 79
Resta rt (MMI) . . . . . . . . . . . . . . . . . . . . . . . . 253
Retractor . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
Reverse gea r . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Reversible cargo floor . . . . . . . . . . . . . . . . . . 7 4
Rewinding (audio/video file) . . . . . . . . . . . . 236
Right control button . . . . . . . . . . . . . . . . . . . . 14
Rims ..... .. .. .... ... ... ..... .. .. .. . 349
Clean ing . . . . . . . . . . . . . . . . . . . . . . . . . . . 355
Ringtone settings . . . . . . . . . . . . . . . . . . . . . 1 85
Roaming
refer to Data connection . . . . . . . . . . . . . . 1 95
Roof emergency operation . . . . . . . . . . . . . . . 50
396
Roof rack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 4
Roof load . . . . . . . . . . . . . . . . . . . . . . . . . . .
7 4
also ref er to Roof rack . . . . . . . . . . . . . . . . . 7 4
Route criteria . . . . . . . . . . . . . . . . . . . . . . . . 213
Route guidan ce
refer to Navigation . . . . . . . . . . . . . . . . . . . 204
Running direc tion (tires)
s
Safe driving habits
Safety 366
254
Airbag system . . . . . . . . . . . . . . . . . . . . . . 271
Belts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263
Cargo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259
Correct seating position . . . . . . . . . . . . . . 255
P edal area . . . . . . . . . . . . . . . . . . . . . . . . . . 259
T ele phone. . . . . . . . . . . . . . . . . . . . . . . . . . 175
Safety belt height adjustment . . . . . . . . . . . 268
Safety belt position . . . . . . . . . . . . . . . . . . . 267
Safety belt height adjustment . . . . . . . . . 268
Safety belts worn by pregnant women . . . 268
Safety belt pretensioner Serv ice and d isposal. . . . . . . . . . . . . . . . . . 270
Safety be lts . . . . . . . . . . . . . . . . . . . . . . 263, 266
Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . 356
Danger to passengers who do not w ear a
saf ety b elt . . . . . . . . . . . . . . . . . . . . . . . . . 264
Fas tening . . . . . . . . . . . . . . . . . . . . . . . . . . 266
Improperly worn . . . . . . . . . . . . . . . . . . . . 269
Not worn . . . . . . . . . . . . . . . . . . . . . . . . . . 264
Safety belt position . . . . . . . . . . . . . . . . . . 267
Safety instructions . . . . . . . . . . . . . . . . . . . 265
Securing child safety seats . . . . . . . . . . . .
306
Special considerat ions for pregnant wom -
en .......... ..... .. ............... 268
Unfastening . . . . . . . . . . . . . . . . . . . . . . . . 268
Warning/indicator light . . . . . . . . . . . . . . 263
Worn p roperly . . . . . . . . . . . . . . . . . . . . . . 265
Safety belt warning light . . . . . . . . . . . . . . . 263
Safety instructions for side curtain airbags . . . . . . . . . . . . . . . 294
for using child safety seats . . . . . . . . . . . . 299
for using safety belts . . . . . . . . . . . . . . . . . 265
Monitoring the Advanced Airbag System 285
Saving fuel Energy consumers . . . . . . . . . . . . . . . . . . . . 18
Recuperation . . . . . . . . . . . . . . . . . . . . . . . . 17