Why Do Relays Use 30, 85, 86, 87, 87a?

Do all or almost all relays use the terminal numbers 30, 85, 86, 87 and 87a?

How did these numbers come to be used?  Why not 1, 2, 3, 4 and 4a or 5?

The UK quattro Network
Automotive component pin assignments
Yes, it's perfectly true. All those little numbers barely perceptibly cast in the bases of automotive relays are standardized! Who knows - the following list may be helpful in emergencies, although it may not be complete or entirely correct:
Ignition and current supply
Code Function
1 Coil, distributor - low voltage
1a To contact breaker I (distributor with 2 separate circuits)
1b To contact breaker II (distributor with 2 separate circuits)
2 Shorting circuit - magneto ignition
4 Coil, distributor - high voltage
4a From coil I (distributor with 2 separate circuits)
4b From coil II (distributor with 2 separate circuits)
7 Ballast resistor terminal to/from distributor
15 Switched + downstream of battery (output of ignition/driving switch)
15a Output at ballast resistor to coil and starter
17 Glow plug and starter switch - Start
19 Glow plug and starter switch - Preheat
30 Input from battery +, direct 12/24 V series-parallel battery switch
30a Input from + terminal of battery II
31 Battery negative terminal, or ground, direct
31a Return line to battery II, negative (12/24 V series-parallel battery switch)
31b Return line to battery negative terminal, or ground via switch or relay (switched negative)
31c Return line to battery I, negative (12/24 V series-parallel battery switch)
XBattery power switched through the load reduction relay
Motors
Code Function
32 Return
33 Main terminal connection
33a Self-parking switch-off
33b Shunt field
33f For 2nd low-speed range
33g For 3rd low-speed range
33h For 4th low-speed range
33L Anticlockwise
33R  Clockwise
Starters
Code Function
45 Separate starter relay, output; starter, input (main current)Two-starter parallel operation - Starting relay for engagement current
45a Output, starter I, Input, starters I and II
45b Output, starter II
 
48 Terminal on starter & on repeating relay for monitoring starting procedure
Turn-signal flashers (pulse generators)
Code Function
49 Input
49a Output
49b Output, 2nd circuit
49c Output, 3rd circuit
Starter control
Code Function
50 Starter control (direct)
50a Series-parallel battery switch - Output for starter controlwith parallel operation of two starters with sequential control
50b Starting relay for sequential control of the engagement currentduring parallel operation of two starters
50c Input at starting relay for starter I
50d Input at starting relay for starter II
50e Start-locking relay Input
50f Start-locking relay Output
50g Start-repeating relay Input
50h Start-repeating relay Output
Alternator
Code Function
51 DC voltage at rectifier
51e DC voltage at rectifier with choke coil for daytime driving
Trailer signals
Code Function
52 Additional signals from trailer to vehicle
Wiper motors
Code Function
53 Wiper motor, input (+)
53a Wiper (+), self-parking switch-off
53b Wiper (shunt winding)
53c Electric windshield-washer pump
53e Wiper (brake winding)
53I Wiper motor with permanent magnet and 3rd brush(for higher speed)
Trailer signals (see also 52)
Code Function
54 Trailer plug connections and lighting combinations, brake light
54g Pneumatic valve for continuous brake in trailer, solenoid-operated
Lighting
Code Function
55 Fog lamp
56 Headlamp
56a High beam, high-beam indicator lamp
56b Low beam
56d Headlamp-flasher
57a Parking lamp
57L Parking lamp, left
57R Parking lamp, right
58 Side-marker, tail, numberplate and instrument panel lamps
58b Taillight changeover for two-wheeled tractors
58c Trailer plug and receptacle assembly for single-conductor tailight with fuse in trailer
58d Variable intensity instrument panel light, tail light and side marker.
58L Numberplate lamp, left
58R Numberplate lamp, right
Alternators and voltage regulators
Code Function
59 A/c voltage output, rectifier input
59a Charging armature, output
59b Tail light armature, output
59c Brake light armature, output
61 Alternator charge-indicator lamp
B+ Battery +
B- Battery -
D+ Dynamo +
D- Dynamo -
DF Dynamo field
DF1 Dynamo field 1
DF2 Dynamo field 2
U,V,W Three-phase alternator terminals
Multi-tone horn and emergency lights
Code Function
71 Input
71a Output to horns 1 & 2 low
71b Output to horns 1 & 2 high
72 Alarm switch - revolving emergency light
Radio, cigarette lighter
Code Function
75 Radio, cigar lighter
76 Speakers
77 Door valve control
Normally closed and changeover switches
Code Function
81 Input
81a Output 1, NC side
81b Output 2, NC side
Normally open switches
Code Function
82 Input
82a Output 1
82b Output 2
82z Input 1
82y Input 2
Multi-position switches
Code Function
83 Input
83a Output, position 1
83b Output, position 2
83L Output, left-hand position
83R Output, right-hand position
Current relays
Code Function
84 Input, actuator and relay contact
84a Output, actuator
84a Output, relay contact
Switching relays
Code Function
85 Output, actuator (end of winding to ground or negative)
86 Input, actuator (start of winding)
86a Start of winding or 1st winding
86b Winding tap or 2nd winding
Relays - N/C and changeover
Code Function
87 Input
87a Output 1(NC side)
87b Output 2
87c Output 3
87z Input 1
87y Input 2
87x Input 3
Relays - N/O and changeover
Code Function
88 Input
88a Output 1
88b Output 2
88c Output 3
88z Input 1
88y Input 2
88x Input 3
Directional signals
Code Function
C Indicator lamp 1
C2 Indicator lamp 2
C0 Main connection for separate indicator circuitsworked by turn signal switch
C3 Indicator lamp 3 (e.g., when towing two trailers)
L Turn-signal lamps, left
R Turn-signal lamps, right
Kerbside Motors Home Page and Contact Information
https://www.isham-research.com/quattro/wiring/Typ85/terminals.html

From Bosch Automotive Handbook, 3rd edition
Terminal Designations (Excerpts from DIN Standard 72 552)
The terminal designations do not identify the conductors, because device
with different terminal designations can be connected at the two ends of
each conductor. If the number of terminal designations is not
sufficient (multiple-contact connections), the terminals are
consecutively numbered using numbers or letters whose representations
of specific functions are not standardized. <>
Terminal Definition
-----------------------------------------------------------------------
IGNITION
1 Ignition coil, ignition distributor, low voltage
-----------------------------------------------------------------------
(Ignition distributor with two separate electrical circuits)
1a to ignition contact breaker I
1b to ignition contact breaker II
-----------------------------------------------------------------------
2 short-circuit terminal (magneto ignition)
4 Ignition coil, ignition distributor, high voltage
-----------------------------------------------------------------------
(ignition distributor with two separate electrical circuits)
4a from ignition coil I, terminal 4
4b from ignition coil II, terminal 4
-----------------------------------------------------------------------
15 Switched + downstream of battery
(output of ignition/driving switch)
15a Output at dropping resistor to ignition coil and starter
-----------------------------------------------------------------------
GLOW PLUG AND STARTER SWITCH
17 Start
19 Preheat
-----------------------------------------------------------------------
BATTERY
30 input from + battery terminal, direct
30a input from + terminal of battery II
(12/24 V series-parallel battery switch)
31 Return line to battery
- battery terminal or ground, direct
31b Return ine to negative battery terminal or ground, via switch
or relay (switched negative)
-----------------------------------------------------------------------
(12/24 V series-parallel battery)
31a Return line to - terminal of battery II
31c Return line to - terminal of battery I
-----------------------------------------------------------------------
ELECTRIC MOTORS
32 Return line
(Polarity reversal possible at terminals 32-33)
33 Main terminal connection
(Polarity reversal possible at terminals 32-33)
33a Self-parking switch-off
33b Shunt field
33f For second lower-speed range
33g For third lower-speed range
33h For fourth lower-speed range
33L Counterclockwise rotation
33R Clockwise rotation
-----------------------------------------------------------------------
STARTER
45 Separate starter relay, output; starter input (main current)
45a Output, starter I
Input, starters I and II (Two-starter parallel operation)
45b Output, starter II (Two-starter parallel operation)
48 Terminal on starter and on start-repeating relay for
monitoring starting procedure
-----------------------------------------------------------------------
TURN SIGNAL FLASHER
49 Input
49a Output
49b Output, second turn-signal circuit
49c Output, third turn-signal circuit
-----------------------------------------------------------------------
STARTER
50 Starter control (direct)
50a Output for starter control
(Series-parallel battery switch)
50b Starter control with parallel operation of two starters with
sequential control
50c Input at starting relay for starter I
(Starting relay for sequential control of the engagement
current during parallel operation of two starters)
50d Input at starting relay for starter I
(Starting relay for sequential control of the engagement
current during parallel operation of two starters)
50e Input, Start-locking relay
50f Output, Start-locking relay
50g Input, Start-repeating relay
50h Output, Start-repeating relay
-----------------------------------------------------------------------
ALTERNATOR
51 DC voltage at rectifier
51e DC voltage at rectifier with choke coil for daytime driving
-----------------------------------------------------------------------
TRAILER SIGNALS
52 Signals from trailer to towing vehicle, general
-----------------------------------------------------------------------
WIPER MOTOR
53 Wiper motor, input (+)
53a Wiper (+), self-parking switch-off
53b Wiper (shunt winding)
53c Electric windshield-washer pump
53e Wiper (brake winding)
53i Wiper motor with permanent magnet and third brush (for higher
speed)
-----------------------------------------------------------------------
TRAILER SIGNAL
54 For lamp combinations and trailer plug connections
TRAILER STOP LAMP
54g Pneumatic valve for additional retarding brake,
electromagnetically actuated
-----------------------------------------------------------------------
LIGHTING
55 Fog lamps
56 Headlamp
56a High beam, high-beam indicator lamp
56b Low beam
56d Headlamp-flasher contact
57 Side-marker lamp: motorcycles, mopeds.
Abroad also cars, trucks, etc.
57a Parking lamp
57L Parking lamp, left
57R Parking lamp, right
58 Side-marker lamps, tail lamps, license-plate lamps and
instrument-panel lamps
58b Tail-lamp changeover for single-axle tractors
58c Trailer plug-and-receptacle assembly for single-conductor
tail-lamp cable with fuse in trailer
58d Variable-intensity instrument-panel lamp, tail-lamp and
side-marker lamp
58L Side-marker lamp, left
58R Side-marker lamp, right; license-plate lamp
-----------------------------------------------------------------------
ALTERNATOR (magneto, generator)
59 AC voltage, output
Rectifier, input
59a Charging armature, output
59b Tail-lamp armature, output
59c Stop-lamp armature, output
61 Alternator charge-indicator lamp
-----------------------------------------------------------------------
TONE-SEQUENCE CONTROL DEVICE
71 Input
71a Output to horns 1 & 2, low
71b Output to horns 1 & 2, high
72 Alarm switch (rotating beacon)
-----------------------------------------------------------------------
INTERIOR
75 Radio, cigarette lighter
76 Speaker
77 Door-valve control
-----------------------------------------------------------------------
SWITCHES
----------(Break-contact and changeover switches)----------------------
81 Input
81a 1st output, break side
81b 2nd output, break side
----------(Make-contact switches)--------------------------------------
82 Input
82a 1st output
82b 2nd output
82z 1st input
82y 2nd input
----------(Multiple-position switches)---------------------------------
83 Input
83a Output, position 1
83b Output, position 2
83L Output, left-hand position
83R Output, right-hand position
-----------------------------------------------------------------------
CURRENT RELAY
84 Input, actuator and relay contact
84a Output, actuator
84b Output, relay contact
-----------------------------------------------------------------------
SWITCHING RELAY
85 Output, actuator (end of winding to ground or negative)
86 Start of winding
86a Start of winding or 1st winding
86b Winding tap or 2nd winding
----------(relay contact for break and changeover contacts)------------
87 Input
87a 1st output (break side)
87b 2nd output
87c 3rd output
87z 1st input
87y 2nd input
87x 3rd input
----------(Relay contact for make contact)-----------------------------
88 Input
----------(Relay contact for make and changeover contacts (make side))-
88a 1st output
88b 2nd output
88c 3rd output
----------(Relay contact for make contact)-----------------------------
88z 1st input
88y 2nd input
88x 3rd input
------------------------------------------------------------------------
ALTERNATOR and VOLTAGE REGULATOR
GENERATOR and GENERATOR REGULATOR
B+ Battery positive
B- Battery negative
D+ Dynamo postive
D- Dynamo negative
DF Dynamo field
DF1 Dynamo field 1
DF2 Dynamo field 2
----------(Alternator with separate rectifier)--------------------------
J Excitation winding positive
K Excitation winding negative
Mp Center point terminal
U,V,W Alternator terminals
------------------------------------------------------------------------
DIRECTION INDICATOR (turn-signal flasher)
C First indicator lamp
C0 Main terminal connection for separate indicator circuits
actuated by the turn-signal switch
C2 Second indicator lamp
C3 Third indicator lamp (e.g., when towing two trailers)
L Turn-signal lamps, left
R Turn-signal lamps, right
------------------------------------------------------------------------
Cross-reference for old and new terminal designations in accordance with
DIN 72 552.
Only terminal designations whose significance has altered are given.
OLD NEW
1 1, 53(wiper), 53e
2 2, 53e
3 53, 53b(wiper)
4 4, 53a, 53b(wiper)
15 15, 49(turn-signal flasher)
15+ 49
15/54 15, 49, 54
16 15a, 15
30 30, 33(motor)
30/51 30, 87, 88(relay)
30f 45
30h 45, 45a
30h I 45a
30h II 45b
30L 33L (motors)
30R 33R (motors)
31 31, 31c, 32(motors)
31a 31a, 31c
31B- B-
50 50, 50b, 50f, 50h
50a 50, 50a, 50e, 50g
50b 50d
50k 50d
50 II 50c
51 51, 59, B+
51 - 59
51a 59
51B+ B+
54 54, 53a, 54g
54/15 15
54d 53(wiper)
54e 33b, 53b(wiper)
54L 49a
58 58, 58L, 58R
58b 58b, 58d
59 59a
85d 31b(alarm switch)
B+30 B+
B+51 B+
D+/61 D+
D-/61 D-
H 71
HL L (L54b)
HR R (R54b)
K C
K0 C0
K1 C, C2
K2 C2
K3 C2, C3
K4 C2, C3
L54 L (L54)
N 55
P C, 57a
PL 57L
PR 57R
R R, 75
R54 R, (R54)
R54b Rb
S 49a, 53(wiper)
S4 49a
SBL (L54)
SBR (R54)
VL L
VR R
+ 15, 49(turn-signal flasher)
53, 53a(wiper)
+2 53a
+15 49
- 1 (ignition coil), 31
------------------------------------------------------------------------
and, while i'm at it, here's some interesting stuff:
Power consumption of vehicle electrical leads (average values)
Backup lamps 25W
Battery ignition 20W
Blower motor 80W
Cigarette lighter 100W
Fog lights 35W each
Fog warning lamp 35W
(red fog light on rear)
Glow plugs 100W each
Headlamps, low beam 55W each
Headlamps, high beam 60W each
Heated rear window 120W
Horns and fanfare horns 25W...40W each
Instrument-panel lamps 2W each
Interior lamp 5W
License-plate lamp 10W
Parking lamp 3W...5W
Radio 10W...15W
Side-marker lamps 4W each
Starting motor for truck 2.2kW...12kW
Starting motor for car 0.8kW...3kW
Stop lamps 18W each
Tail lamps 5W each
Turn-signal lamps 21W each
Vehicle heater 20W...60W
Windshield wiper 90W
https://www.members.shaw.ca/bilbo/bosch.html

Test this Tuesday at 9am local standard time at your nearest university or MECP approved testing center. You will be answering 150 questions on everything above.

>.<

Good Luck?

PS. Thanks HWW for the "extended" answer.

Good and informative answer.