1. Product profile
1.1 General description
High-speed switching diodes, encapsulated in small Surface-Mounted Device (SMD)
plastic packages.
1.2 Features
1.3 Applications
nHigh-speed switching
nGeneral-purpose switching
1.4 Quick reference data
[1] When switched from IF= 10 mA to IR= 10 mA; RL= 100 Ω; measured at IR= 1 mA.
BAV756S; BAW56 series
High-speed switching diodes
Rev. 05 — 26 November 2007 Product data sheet
Table 1. Product overview
Type number Package Package
configuration Configuration
NXP JEITA JEDEC
BAV756S SOT363 SC-88 - very small quadruple common
anode/common cathode
BAW56 SOT23 - TO-236AB small dual common anode
BAW56M SOT883 SC-101 - leadless ultra
small dual common anode
BAW56S SOT363 SC-88 - very small quadruple common
anode/common anode
BAW56T SOT416 SC-75 - ultra small dual common anode
BAW56W SOT323 SC-70 - very small dual common anode
nHigh switching speed: trr ≤4ns nLow capacitance: Cd≤2pF
nLow leakage current nReverse voltage: VR≤90 V
nSmall SMD plastic packages
Table 2. Quick reference data
Symbol Parameter Conditions Min Typ Max Unit
Per diode
IRreverse current VR= 80 V - - 0.5 µA
VRreverse voltage - - 90 V
trr reverse recovery time [1] --4ns
BAV756S_BAW56_SER_5 © NXP B.V. 2007. All rights reserved.
Product data sheet Rev. 05 — 26 November 2007 2 of 15
NXP Semiconductors BAV756S; BAW56 series
High-speed switching diodes
2. Pinning information
Table 3. Pinning
Pin Description Simplified outline Symbol
BAV756S
1 anode (diode 1)
2 cathode (diode 2)
3 common anode (diode 2 and
diode 3)
4 cathode (diode 3)
5 anode (diode 4)
6 common cathode (diode 1
and diode 4)
BAW56; BAW56T; BAW56W
1 cathode (diode 1)
2 cathode (diode 2)
3 common anode
BAW56M
1 cathode (diode 1)
2 cathode (diode 2)
3 common anode
BAW56S
1 cathode (diode 1)
2 cathode (diode 2)
3 common anode (diode 3 and
diode 4)
4 cathode (diode 3)
5 cathode (diode 4)
6 common anode (diode 1 and
diode 2)
132
4
56
006aab103
13
6
2
54
006aaa144
12
3
006aab099
12
3
3
1
2
Transparent
top view
006aab099
12
3
132
4
56
006aab102
13
6
2
54
BAV756S_BAW56_SER_5 © NXP B.V. 2007. All rights reserved.
Product data sheet Rev. 05 — 26 November 2007 3 of 15
NXP Semiconductors BAV756S; BAW56 series
High-speed switching diodes
3. Ordering information
4. Marking
[1] * = -: made in Hong Kong
* = p: made in Hong Kong
* = t: made in Malaysia
* = W: made in China
5. Limiting values
Table 4. Ordering information
Type number Package
Name Description Version
BAV756S SC-88 plastic surface-mounted package; 6 leads SOT363
BAW56 - plastic surface-mounted package; 3 leads SOT23
BAW56M SC-101 leadless ultra small plastic package; 3 solder lands;
body 1.0 ×0.6 ×0.5 mm SOT883
BAW56S SC-88 plastic surface-mounted package; 6 leads SOT363
BAW56T SC-75 plastic surface-mounted package; 3 leads SOT416
BAW56W SC-70 plastic surface-mounted package; 3 leads SOT323
Table 5. Marking codes
Type number Marking code[1]
BAV756S A7*
BAW56 A1*
BAW56M S5
BAW56S A1*
BAW56T A1
BAW56W A1*
Table 6. Limiting values
In accordance with the Absolute Maximum Rating System (IEC 60134).
Symbol Parameter Conditions Min Max Unit
Per diode
VRRM repetitive peak reverse
voltage -90V
VRreverse voltage - 90 V
IFforward current
BAV756S Ts=60°C - 250 mA
BAW56 Tamb ≤25 °C - 215 mA
BAW56M Tamb ≤25 °C - 150 mA
BAW56S Ts=60°C - 250 mA
BAW56T Ts=90°C - 150 mA
BAW56W Tamb ≤25 °C - 150 mA
BAV756S_BAW56_SER_5 © NXP B.V. 2007. All rights reserved.
Product data sheet Rev. 05 — 26 November 2007 4 of 15
NXP Semiconductors BAV756S; BAW56 series
High-speed switching diodes
[1] Tj=25°C prior to surge.
[2] Device mounted on an FR4 Printed-Circuit Board (PCB), single-sided copper, tin-plated and standard
footprint.
[3] Reflow soldering is the only recommended soldering method.
[4] Single diode loaded.
6. Thermal characteristics
IFRM repetitive peak forward
current - 500 mA
IFSM non-repetitive peak forward
current square wave [1]
tp=1µs-4A
tp=1ms - 1 A
tp= 1 s - 0.5 A
Ptot total power dissipation [2]
BAV756S Ts=60°C - 350 mW
BAW56 Tamb ≤25 °C - 250 mW
BAW56M Tamb ≤25 °C[3] - 250 mW
BAW56S Ts=60°C - 350 mW
BAW56T Ts=90°C[4] - 170 mW
BAW56W Tamb ≤25 °C - 200 mW
Per device
IFforward current
BAV756S Ts=60°C - 100 mA
BAW56 Tamb ≤25 °C - 125 mA
BAW56M Tamb ≤25 °C - 75 mA
BAW56S Ts=60°C - 100 mA
BAW56T Ts=90°C - 75 mA
BAW56W Tamb ≤25 °C - 130 mA
Tjjunction temperature - 150 °C
Tamb ambient temperature −65 +150 °C
Tstg storage temperature −65 +150 °C
Table 6. Limiting values
…continued
In accordance with the Absolute Maximum Rating System (IEC 60134).
Symbol Parameter Conditions Min Max Unit
Table 7. Thermal characteristics
Symbol Parameter Conditions Min Typ Max Unit
Per diode
Rth(j-a) thermal resistance from
junction to ambient in free air [1]
BAW56 - - 500 K/W
BAW56M [2] - - 500 K/W
BAW56W - - 625 K/W
BAV756S_BAW56_SER_5 © NXP B.V. 2007. All rights reserved.
Product data sheet Rev. 05 — 26 November 2007 5 of 15
NXP Semiconductors BAV756S; BAW56 series
High-speed switching diodes
[1] Device mounted on an FR4 PCB, single-sided copper, tin-plated and standard footprint.
[2] Reflow soldering is the only recommended soldering method.
7. Characteristics
[1] Pulse test: tp≤300 µs; δ≤0.02.
[2] When switched from IF= 10 mA to IR= 10 mA; RL= 100 Ω; measured at IR= 1 mA.
[3] When switched from IF= 10 mA; tr=20ns.
Rth(j-sp) thermal resistance from
junction to solder point
BAV756S - - 255 K/W
BAW56 - - 360 K/W
BAW56S - - 255 K/W
BAW56T - - 350 K/W
BAW56W - - 300 K/W
Table 7. Thermal characteristics
…continued
Symbol Parameter Conditions Min Typ Max Unit
Table 8. Characteristics
T
amb
=25
°
C unless otherwise specified.
Symbol Parameter Conditions Min Typ Max Unit
Per diode
VFforward voltage [1]
IF= 1 mA - - 715 mV
IF= 10 mA - - 855 mV
IF=50mA --1V
IF= 150 mA - - 1.25 V
IRreverse current VR=25V --30nA
VR= 80 V - - 0.5 µA
VR=25V;T
j= 150 °C--30µA
VR=80V;T
j= 150 °C - - 150 µA
Cddiode capacitance VR= 0 V; f = 1 MHz - - 2 pF
trr reverse recovery time [2] --4ns
VFR forward recovery voltage [3] - - 1.75 V
BAV756S_BAW56_SER_5 © NXP B.V. 2007. All rights reserved.
Product data sheet Rev. 05 — 26 November 2007 6 of 15
NXP Semiconductors BAV756S; BAW56 series
High-speed switching diodes
(1) Tamb = 150 °C
(2) Tamb =85°C
(3) Tamb =25°C
(4) Tamb =−40 °C
Based on square wave currents.
Tj=25°C; prior to surge
Fig 1. Forward current as a function of forward
voltage; typical values Fig 2. Non-repetitive peak forward current as a
function of pulse duration; maximum values
(1) Tamb = 150 °C
(2) Tamb =85°C
(3) Tamb =25°C
(4) Tamb =−40 °C
f = 1 MHz; Tamb =25°C
Fig 3. Reverse current as a function of reverse
voltage; typical values Fig 4. Diode capacitance as a function of reverse
voltage; typical values
006aab109
VF (V)
0.2 1.41.00.6
1
10
102
103
IF
(mA)
10−1
(1) (2) (3) (4)
mbg704
10
1
102
IFSM
(A)
10−1
tp (µs)
110
4
103
10 102
006aab110
10−2
10−4
10−3
10
1
10−1
102
IR
(µA)
10−5
VR (V)
0 1008040 6020
(1)
(2)
(3)
(4)
025
VR (V)
2.5
0
0.5
mbh191
1.0
1.5
2.0
5
Cd
(pF)
10 15 20
BAV756S_BAW56_SER_5 © NXP B.V. 2007. All rights reserved.
Product data sheet Rev. 05 — 26 November 2007 7 of 15
NXP Semiconductors BAV756S; BAW56 series
High-speed switching diodes
8. Test information
(1) IR=1mA
Input signal: reverse pulse rise time tr= 0.6 ns; reverse voltage pulse duration tp= 100 ns; duty cycle δ= 0.05
Oscilloscope: rise time tr= 0.35 ns
Fig 5. Reverse recovery time test circuit and waveforms
Input signal: forward pulse rise time tr= 20 ns; forward current pulse duration tp≥100 ns; duty cycle δ≤0.005
Fig 6. Forward recovery voltage test circuit and waveforms
trr
(1)
+ IFt
output signal
trtpt
10 %
90 %
VR
input signal
V = VR + IF × RS
RS = 50 ΩIF
D.U.T.
Ri = 50 Ω
SAMPLING
OSCILLOSCOPE
mga881
trt
tp
10 %
90 %
I
input signal
RS = 50 Ω
I
Ri = 50 Ω
OSCILLOSCOPE
1 kΩ450 Ω
D.U.T.
mga882
VFR
t
output signal
V
BAV756S_BAW56_SER_5 © NXP B.V. 2007. All rights reserved.
Product data sheet Rev. 05 — 26 November 2007 8 of 15
NXP Semiconductors BAV756S; BAW56 series
High-speed switching diodes
9. Package outline
Fig 7. Package outline BAW56 (SOT23/TO-236AB) Fig 8. Package outline BAW56M (SOT883/SC-101)
Fig 9. Package outline BAV756S and
BAW56S (SOT363/SC-88) Fig 10. Package outline BAW56T (SOT416/SC-75)
Fig 11. Package outline BAW56W (SOT323/SC-70)
04-11-04Dimensions in mm
0.45
0.15
1.9
1.1
0.9
3.0
2.8
2.5
2.1 1.4
1.2
0.48
0.38 0.15
0.09
12
3
03-04-03Dimensions in mm
0.62
0.55
0.55
0.47 0.50
0.46
0.65
0.20
0.12
3
21
0.30
0.22
0.30
0.22
1.02
0.95
0.35
06-03-16Dimensions in mm
0.25
0.10
0.3
0.2
pin 1
index
1.3
0.65
2.2
2.0 1.35
1.15
2.2
1.8 1.1
0.8
0.45
0.15
132
465
04-11-04Dimensions in mm
0.95
0.60
1.8
1.4
1.75
1.45 0.9
0.7
0.25
0.10
1
0.30
0.15
12
30.45
0.15
04-11-04Dimensions in mm
0.45
0.15
1.1
0.8
2.2
1.8
2.2
2.0 1.35
1.15
1.3
0.4
0.3 0.25
0.10
12
3
BAV756S_BAW56_SER_5 © NXP B.V. 2007. All rights reserved.
Product data sheet Rev. 05 — 26 November 2007 9 of 15
NXP Semiconductors BAV756S; BAW56 series
High-speed switching diodes
10. Packing information
[1] For further information and the availability of packing methods, see Section 14.
[2] T1: normal taping
[3] T2: reverse taping
11. Soldering
Table 9. Packing methods
The indicated -xxx are the last three digits of the 12NC ordering code.
[1]
Type number Package Description Packing quantity
3000 10000
BAV756S SOT363 4 mm pitch, 8 mm tape and reel; T1 [2] -115 -135
4 mm pitch, 8 mm tape and reel; T2 [3] -125 -165
BAW56 SOT23 4 mm pitch, 8 mm tape and reel -215 -235
BAW56M SOT883 2 mm pitch, 8 mm tape and reel - -315
BAW56S SOT363 4 mm pitch, 8 mm tape and reel; T1 [2] -115 -135
4 mm pitch, 8 mm tape and reel; T2 [3] -125 -165
BAW56T SOT416 4 mm pitch, 8 mm tape and reel -115 -135
BAW56W SOT323 4 mm pitch, 8 mm tape and reel -115 -135
Fig 12. Reflow soldering footprint BAW56 (SOT23/TO-236AB)
solder resist
occupied area
solder lands
solder paste
Dimensions in mm
sot023
1.00
0.60
(3x)
1.30
12
3
2.50
3.00
0.85
2.70
2.90
0.50 (3x)
0.60 (3x)
3.30
0.85
BAV756S_BAW56_SER_5 © NXP B.V. 2007. All rights reserved.
Product data sheet Rev. 05 — 26 November 2007 10 of 15
NXP Semiconductors BAV756S; BAW56 series
High-speed switching diodes
Fig 13. Wave soldering footprint BAW56 (SOT23/TO-236AB)
Reflow soldering is the only recommended soldering method.
Fig 14. Reflow soldering footprint BAW56M (SOT883/SC-101)
sot023
4.004.60
2.80
4.50
1.20
3.40
3
21
1.20 (2x)
preferred transport direction during soldering
Dimensions in mm
solder resist
occupied area
solder lands
solder lands
solder paste
solder resist
occupied area Dimensions in mm
1.30
0.30R = 0.05 (12×) R = 0.05 (12×)
0.60 0.70 0.80
0.90
0.30
(2×)
0.35
(2×)
0.20
0.40
(2×)
0.50
(2×)
0.25
(2×)
0.30
0.40
0.50
BAV756S_BAW56_SER_5 © NXP B.V. 2007. All rights reserved.
Product data sheet Rev. 05 — 26 November 2007 11 of 15
NXP Semiconductors BAV756S; BAW56 series
High-speed switching diodes
Fig 15. Reflow soldering footprint BAV756S and BAW56S (SOT363/SC-88)
Fig 16. Wave soldering footprint BAV756S and BAW56S (SOT363/SC-88)
sot363
1.20
2.40
0.50
(4×)
0.40
(2×)0.90 2.10
0.50
(4×)
0.60
(2×)
2.35
2.65
solder lands
solder resist
occupied area
solder paste
Dimensions in mm
solder lands
solder resist
occupied area
1.15
3.75
transport direction during soldering
1.000.30 4.00
4.50
5.25
sot363
Dimensions in mm
BAV756S_BAW56_SER_5 © NXP B.V. 2007. All rights reserved.
Product data sheet Rev. 05 — 26 November 2007 12 of 15
NXP Semiconductors BAV756S; BAW56 series
High-speed switching diodes
Fig 17. Reflow soldering footprint BAW56T (SOT416/SC-75)
Fig 18. Reflow soldering footprint BAW56W (SOT323/SC-70)
Fig 19. Wave soldering footprint BAW56W (SOT323/SC-70)
solder resist occupied area
solder lands solder pasteDimensions in mm
msa438
2.0
0.6
(3x)
0.7
1.5
1
2
3
1.1
2.2
0.5
(3x)
0.85
0.6
1.9
msa429
0.852.35
0.55
(3×)
1.3250.75
2.40
2.65
1.30
3
2
1
0.60
(3×)
0.50
(3×)1.90
solder lands
solder resist
occupied area
solder paste
Dimensions in mm
msa419
4.00
4.60
2.103.65
1.15
2.70
3
2
10.90
(2×)
preferred transport direction during soldering
solder lands
solder resist
occupied area
Dimensions in mm
BAV756S_BAW56_SER_5 © NXP B.V. 2007. All rights reserved.
Product data sheet Rev. 05 — 26 November 2007 13 of 15
NXP Semiconductors BAV756S; BAW56 series
High-speed switching diodes
12. Revision history
Table 10. Revision history
Document ID Release date Data sheet status Change notice Supersedes
BAV756S_BAW56_SER_5 20071126 Product data sheet - BAV756S_2
BAW56_4
BAW56S_2
BAW56T_2
BAW56W_4
Modifications: •The format of this data sheet has been redesigned to comply with the new identity
guidelines of NXP Semiconductors.
•Legal texts have been adapted to the new company name where appropriate.
•Type number BAW56M added
•Section 1.1 “General description”: amended
•Table 1 “Product overview”: added
•Table 2 “Quick reference data”: added
•Table 6 “Limiting values”: for BAV756S, BAW56, BAW56S, BAW56T and BAW56W
change of VRRM maximum value from 85 V to 90 V
•Table 6 “Limiting values”: for BAV756S, BAW56, BAW56S, BAW56T and BAW56W
change of VRmaximum value from 75 V to 90 V
•Table 8 “Characteristics”: for BAV756S, BAW56, BAW56S, BAW56T and BAW56W
change of IRcondition VR from 75 V to 80 V for Tj=25°C
•Table 8 “Characteristics”: for BAV756S change of IRmaximum value from 2.5 µAto0.5µA
for Tj=25°C
•Table 8 “Characteristics”: for BAW56, BAW56S, BAW56T and BAW56W change of
IRmaximum value from 1 µA to 0.5 µA for Tj=25°C
•Table 8 “Characteristics”: for BAV756S, BAW56, BAW56S, BAW56T and BAW56W
change of IRcondition VR from 75 V to 80 V for Tj= 150 °C
•Table 8 “Characteristics”: for BAV756S change of IRmaximum value from 60 µA to 30 µA
for IRcondition VR=25V; T
j= 150 °C
•Table 8 “Characteristics”: for BAV756S change of IRmaximum value from 100 µA to
150 µA for Tj= 150 °C
•Table 8 “Characteristics”: for BAW56, BAW56S, BAW56T and BAW56W change of
IRmaximum value from 50 µA to 150 µA for Tj= 150 °C
•Section 8 “Test information”: added
•Section 10 “Packing information”: added
•Section 11 “Soldering”: added
•Section 13 “Legal information”: updated
BAV756S_2 19971021 Product specification - BAV756S_1
BAW56_4 20030325 Product specification - BAW56_3
BAW56S_2 19971021 Product specification - BAW56S_1
BAW56T_2 19971219 Product specification - -
BAW56W_4 19990511 Product specification - BAW56W_3
BAV756S_BAW56_SER_5 © NXP B.V. 2007. All rights reserved.
Product data sheet Rev. 05 — 26 November 2007 14 of 15
NXP Semiconductors BAV756S; BAW56 series
High-speed switching diodes
13. Legal information
13.1 Data sheet status
[1] Please consult the most recently issued document before initiating or completing a design.
[2] The term ‘short data sheet’ is explained in section “Definitions”.
[3] The product status of device(s) described in this document may have changed since this document was published and may differ in case of multiple devices. The latest product status
information is available on the Internet at URL http://www.nxp.com.
13.2 Definitions
Draft — The document is a draft version only. The content is still under
internal review and subject to formal approval, which may result in
modifications or additions. NXP Semiconductors does not give any
representations or warranties as to the accuracy or completeness of
information included herein and shall have no liability for the consequences of
use of such information.
Short data sheet — A short data sheet is an extract from a full data sheet
with the same product type number(s) and title. A short data sheet is intended
for quick reference only and should not be relied upon to contain detailed and
full information. For detailed and full information see the relevant full data
sheet, which is available on request via the local NXP Semiconductors sales
office. In case of any inconsistency or conflict with the short data sheet, the
full data sheet shall prevail.
13.3 Disclaimers
General — Information in this document is believed to be accurate and
reliable. However, NXP Semiconductors does not give any representations or
warranties, expressed or implied, as to the accuracy or completeness of such
information and shall have no liability for the consequences of use of such
information.
Right to make changes — NXP Semiconductors reserves the right to make
changes to information published in this document, including without
limitation specifications and product descriptions, at any time and without
notice. This document supersedes and replaces all information supplied prior
to the publication hereof.
Suitability for use — NXP Semiconductors products are not designed,
authorized or warranted to be suitable for use in medical, military, aircraft,
space or life support equipment, nor in applications where failure or
malfunction of an NXP Semiconductors product can reasonably be expected
to result in personal injury, death or severe property or environmental
damage. NXP Semiconductors accepts no liability for inclusion and/or use of
NXP Semiconductors products in such equipment or applications and
therefore such inclusion and/or use is at the customer’s own risk.
Applications — Applications that are described herein for any of these
products are for illustrative purposes only. NXP Semiconductors makes no
representation or warranty that such applications will be suitable for the
specified use without further testing or modification.
Limiting values — Stress above one or more limiting values (as defined in
the Absolute Maximum Ratings System of IEC 60134) may cause permanent
damage to the device. Limiting values are stress ratings only and operation of
the device at these or any other conditions above those given in the
Characteristics sections of this document is not implied. Exposure to limiting
values for extended periods may affect device reliability.
Terms and conditions of sale — NXP Semiconductors products are sold
subject to the general terms and conditions of commercial sale, as published
at http://www.nxp.com/profile/terms, including those pertaining to warranty,
intellectual property rights infringement and limitation of liability, unless
explicitly otherwise agreed to in writing by NXP Semiconductors. In case of
any inconsistency or conflict between information in this document and such
terms and conditions, the latter will prevail.
No offer to sell or license — Nothing in this document may be interpreted
or construed as an offer to sell products that is open for acceptance or the
grant, conveyance or implication of any license under any copyrights, patents
or other industrial or intellectual property rights.
13.4 Trademarks
Notice: All referenced brands, product names, service names and trademarks
are the property of their respective owners.
14. Contact information
For additional information, please visit: http://www.nxp.com
For sales office addresses, send an email to: salesaddresses@nxp.com
Document status[1][2] Product status[3] Definition
Objective [short] data sheet Development This document contains data from the objective specification for product development.
Preliminary [short] data sheet Qualification This document contains data from the preliminary specification.
Product [short] data sheet Production This document contains the product specification.
NXP Semiconductors BAV756S; BAW56 series
High-speed switching diodes
© NXP B.V. 2007. All rights reserved.
For more information, please visit: http://www.nxp.com
For sales office addresses, please send an email to: salesaddresses@nxp.com
Date of release: 26 November 2007
Document identifier: BAV756S_BAW56_SER_5
Please be aware that important notices concerning this document and the product(s)
described herein, have been included in section ‘Legal information’.
15. Contents
1 Product profile . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 General description. . . . . . . . . . . . . . . . . . . . . . 1
1.2 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.3 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.4 Quick reference data. . . . . . . . . . . . . . . . . . . . . 1
2 Pinning information. . . . . . . . . . . . . . . . . . . . . . 2
3 Ordering information. . . . . . . . . . . . . . . . . . . . . 3
4 Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5 Limiting values. . . . . . . . . . . . . . . . . . . . . . . . . . 3
6 Thermal characteristics. . . . . . . . . . . . . . . . . . . 4
7 Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . 5
8 Test information. . . . . . . . . . . . . . . . . . . . . . . . . 7
9 Package outline . . . . . . . . . . . . . . . . . . . . . . . . . 8
10 Packing information. . . . . . . . . . . . . . . . . . . . . . 9
11 Soldering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
12 Revision history. . . . . . . . . . . . . . . . . . . . . . . . 13
13 Legal information. . . . . . . . . . . . . . . . . . . . . . . 14
13.1 Data sheet status . . . . . . . . . . . . . . . . . . . . . . 14
13.2 Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
13.3 Disclaimers. . . . . . . . . . . . . . . . . . . . . . . . . . . 14
13.4 Trademarks. . . . . . . . . . . . . . . . . . . . . . . . . . . 14
14 Contact information. . . . . . . . . . . . . . . . . . . . . 14
15 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
