Agilent Part No. 08703- 90 20 3
Printed in USA
July 2001
Agilent Technologies
Lightwave Division
3910 Brickway Boulevard
Santa Rosa, CA 95403, USA
Notice.
The information contained in
this document is subject to
change without notice. Companies, names, and data used in
examples herein are fictitious
unless otherwise noted. Agilent Technologies makes no
warranty of any kind with
regard to this material, including but not limited to, the
implied warranties of merchantability and fitness for a
particular purpose. Agilent
Technologies shall not be liable
for errors contained herein or
for incidental or consequential
damages in connection with
the furnishing, performance, or
use of this material.
Restricted Rights Legend.
Use, duplication, or disclosure
by the U.S. Government is subject to restrictions as set forth
in subparagrap h (c) (1 ) (i i) of
the Rights in Technical Data
and Computer Software clause
at DFARS 252.227-7013 for
DOD agencies, and subparagraphs (c) (1) and (c) (2) of
the Commercial Computer
Software Restricted Rights
clause at FAR 52.227-19 for
other agencies.
Warranty.
This Agilent Technologies
instrument product is warranted against defects in material and workmanship for a
period of one yea r fro m date of
shipment. During the warranty period, Agilent Technologies will, at its option, either
repair or replace products
which prove to be defective.
For warranty service or repair,
this product must be returned
to a service facility designated
by Agilent Technologies. Buyer
shall prepay shipping charges
to Agilent Technologies and
Agilent Technologies shall pay
shipping charges to return the
product to Buyer. However,
Buyer shall pay all shipping
charges, duties, and taxes for
products returned to Agilent
Technologies from another
country.
Agilent Technologies warrants
that its software and firmware
designated by Agilent Technologies for use with an instrument will execute its
programming instructions
when properly installed on that
instrument. Agilent Technologies does not warrant that the
operation of the instrument, or
software, or firmware will be
uninterrupted or error-free.
Limitation of Warranty.
The foregoing warranty shall
not apply to defects resulting
from improper or inadequate
maintenance by Buyer,
Buyer-supplied software or
interfacing, unauthorized modification or misuse, operation
outside of the environmental
specifications for the product,
or improper site preparation or
maintenance.
No other warranty is
expressed or implied. Agilent
Technologies specifically disclaims the implied warranties
of merchantability and fitness
for a particular purpose.
Exclusive Remedies.
The remedies provided herein
are buyer's sole and exclusive
remedies. Agilent Technologies
shall not be liable for any
direct, indirect, special, incidental, or consequential damages, whether based on
contract, tort, or any other
legal theory.
Safety Symbols.
CAUTION
The caution sign denotes a
hazard. It calls attention to a
procedure which, if not correctly performed or adhered
to, could result in damage to or
destruction of the product. Do
not proceed beyond a caution
sign until the indicated conditions are fully understood and
met.
WARNING
The warning sign denotes a
hazard. It calls attention to a
procedure which, if not correctly performed or adhered
to, could result in injury or loss
of life. Do not proceed beyond
a warning sign until the indicated conditions are fully
understood and met.
The instruction manual symbol. The product is marked with this
warning symbol when
it is necessary for the
user to refer to the
instructions in the
manual.
The laser radiation
symbol. This warning
symbol is marked on
products which have a
laser output.
The AC symbol is used
to indicate the required
nature of the line module input power.
| The ON symbols are
used to mark the positions of the instrument
power line switch.
❍ The OFF symbols
are used to mark the
positions of the instrument power line
switch.
The CE mark is a registered trademark of the
European Community.
The CSA mark is a registered trademar k of
the Canadian Standards Association.
The C-Tick mark is a
registered trademark of
the Australian Spectrum Management
Agency.
This text denotes the
ISM1-A
instrument is an Industrial Scientific and
Medical Group 1 Class
A product.
Typographi c al C on v ent io ns .
The following conventions are
used in this book:
Keytype for keys or text lo cated
on the keyboard or ins tr ume nt.
Softkeytype for key names that
are displayed on the instrument’s screen.
Displaytype for words or
characters displayed on the
computer’s screen or instrument’s display.
Usertype for words or charac-
ters that you type or enter.
Emphasis type for words or
characters that emphasize
some point or that are used as
place holders for text that you
type.
2
Additional Warranty Information
Additional Warranty Information
If repair is necessary, send the analyzer to the nearest Agilent Technologies service center with a
description of any failed test and any error message. Ship the analyzer using the original packaging
materials. Returning the analyzer in anything other than the original packaging may result in
non-warranted damage. A table listing of Agilent Technologies sales and service offices is provided at
the end of this document.
General Safety Cons i derations
This product has been designed and tested in accordance with IEC Publication 1010, Safety
Requirements for Electronic Measuring Apparatus, and has been supplied in a safe
condition. The instruction documentation contains information and warnings which must be
followed by the user to ensure safe operation and to maintain the product in a safe condition.
WARNINGIf this product is not used as specified, the protection provided by the
equipment could be impaired. This product must be used in a normal
condition (in which all means for protection are intact) only.
WARNINGNo operator serviceable parts inside. Refer servicing to qualified service
personnel. To prevent electrical shock do not remove covers.
WARNINGTo prevent electrical shock, disconnect the instrument from mains before
cleaning. Use a dry cloth or one slightly dampened with water to clean the
external case parts. Do not attempt to clean internally.
WARNINGInstall the instrument according to the enclosure protection provided. This
instrument does not protect against the ingress of water. This instrument
protects against finger access to hazardous parts within the enclosure.
CAUTIONDo not use too much liquid in cleaning the instrument. Water can enter the
Installing Your Agilent 8703B 1
Verify the Shipment 2
Familiarize Yourself with the Front and Rear Panels 4
Install the Laser Output/Laser Input Cable 7
Set up a static-safe workstation 8
Meet Environmental Requirements 9
Meet Electrical Requirements 10
Configuring for Bench Top or Rack Mount Use 13
Configuring for Printers or Plotters 17
Perform the Self-Test 23
Configure the Agilent 8703B 24
Agilent Technologies Service Offices 28
5
Contents
6
Installing Your Agilent8703B
Installing Your Agilent 8703B
This chapter shows you how to install your Agilent 8703B and confirm the correct operation,
by following the steps below:
WARNINGThis is a Safety Class I product (provided with a protective earthing ground
incorporated in the power cord). The mains plug shall only be inserted in a
socket outlet provided with a protective earth contact. Any interruption of
the protective conductor, inside or outside the instrument, is likely to make
the instrument dangerous. Intentional interruption is prohibited.
CAUTIONBefore switching on this instrument, make sure that the Agilent 8703B line
voltage selector switch is set to the voltage of the power supply and the correct
fuse is installed. Assure the supply voltage is in the specified range.
CAUTIONIf this product is to be energized via an autotransformer make sure the common
terminal is connected to the neutral (grounded side of the mains supply).
CAUTIONThis product is designed for use in Installation Category II and Pollution
Degree 2 per IEC 61010-1 and 664 respectively.
CAUTIONVENTILATION REQUIREMENTS: When installing the product in a cabinet, the
convection into and out of the product must not be restricted. The ambient
temperature (outside the cabinet) must be less than the maximum operating
temperature of the product by 4° C for every 100 watts dissipated in the
cabinet. If the total power dissipated in the cabinet is greater that 800 watts,
then forced convection must be used.
1
Installing Yo ur Agilent8703B
e
Step 1. Verify the Shipment
WARNINGThe Agilent 8703B weighs approximately 150 pounds with the packing
materials. Use at least two people, and correct lifting techniques, to unpack
the analyzer.
1. Unpack the contents of all the shipping containers.
dg61
1. Carefully inspect the Agilent 8703B to ensure that it was not damaged during shipment.
dg62e
NOTEIf your Agilent 8703B was damaged during shipment, contact your nearest Agilent
Technologies office or sales representative. A list of Agilent Technologies sales and
service offices is provided in “Agilent Technologies Service Offices” on page 30.
2
2. Verify that all the accessories have been included with the Agilent 8703B.
Installing Your Agilent8703B
Item
Number
108703-90203Installation Guide
208703-90201User's Guide
308720-90204Reference
408703-90202Programmer’s Guide
508703-10202CD-ROM
61005-0955Optical Cable SPC 0.4 M
785131ETest Port Cable 3.5 mm (Female)
8unique to countryAC power cable
9
10
Part Number Description
Rack Flange Kit (Option 908 only)
5063-9212
5063-9216
5063-9220
5063-9223
88.1mm High (2)
221.5mm High (2)
Rack Flange Kit with Handles (Option 909 only)
88.1mm High (2)
221.5mm High (2)
3
Installing Yo ur Agilent8703B
Step 2. Familiarize Yourself with the Front and Rear Panels
Front Panel
CAUTIONDo not mistake the line switch for the disk eject button. See the figure below. If
the line switch is mistakenly pushed, the instrument will be turned off, losing
all settings and data that have not been saved.
1 LINE (power on/off) switch9 ENTRY block
2 Display10 INSTRUMENT STATE function block
3 Disk drive 11 Preset key
4 Disk eject button12 PORT 1 andPORT 2
5 Softkeys13 OPTICAL OUTPUT and OPTICAL RECEIVER ports
6 STIMULUS function block14 LASER OUTPUT and LASER INPUT ports
7 RESPONSE function block15 Internal LASER ON/OFF switch
8 ACTIVE CHANNEL keys
4
Installing Your Agilent8703B
Laser Warning Labels
The 8703B is shipped with the following warning labels. For instruments used outside of the
USA, both laser aperture and laser warning labels will be included with the shipment. (The
labels are located in the same box as this manual.) Place these labels directly over the USA
laser warning and aperture labels.
5
Installing Yo ur Agilent8703B
Rear Panel
1 EXTERNAL MONITOR: VGA
2 GPIB connector
3 EXT ALC INPUT
4 PARALLEL interface
5 RS-232 interface
6 KEYBOARD input (mini-DIN)
7 Power cord receptacle, with fuse
8 Line voltage selector switch
9 EXTERNAL REFERENCE INPUT
10 AUXILIARY INPUT
11 EXTERNAL AM connector
12 EXTERNAL TRIGGER connector
13 TEST SEQUENCE connector
14 LIMIT TEST connector
15 MEASURE RESTART connector
16 TEST SET INTERCONNECT
17 BIAS INPUTS and fuses
18 Serial number plate
19 REMOTE SHUTDOWN
6
Installing Your Agilent8703B
Step 3. Install the Laser Output/Laser Input Cable
• Open the laser cover to access the laser output port, and connect the optical cable (part
number 1005-0955) between LASER OUTPUT and LASER INPUT. The cable is part of the
analyzer shipment.
WARNINGTo prevent accidental exposure to laser light, always verify the laser
key-switch is in the OFF position before removing or connecting fiber-optic
cables, adapters, or devices under test. Never remove or connect fiber-optic
cables, adapters, or devices while a measurement is in progress.
7
Installing Yo ur Agilent8703B
Step 4. Set up a static-safe workstation
• Set up a static-safe workstation. Electrostatic discharge (ESD) can damage or destroy
electronic components.
• static-control table mat and earth ground wire: part number 9300-0797
• wrist-strap cord: part number 9300-0980
• wrist-strap: part number 9300-1367
• heel-straps: part number 9300-1308
• floor mat: not available through Agilent Technologies
8
Installing Your Agilent8703B
Step 5. Meet Environmental Requirements
CAUTIONInstall the instrument so that the ON/OFF switch is readily identifiable and is
easily reached by the operator. The ON/OFF switch or the detachable power
cord is the instrument disconnecting device. It disconnects the mains circuits
from the mains supply before other parts of the instrument. Alternately, an
externally installed switch or circuit breaker (which is readily identifiable and
is easily reached by the operator) may be used as a disconnecting device.
1. Ensure the operating environment meets the following requirements. Some performance
parameters are specified for 25 °C ±5 °C. Refer to the Reference for information on the
environmental compatibility of warranted performance.
Requirements for Operating Environment
Useindoor
Temperature+20 °C to +30 °C
Humidity5% to 95% at +30 °C (non-condensing)
Altitude0 to 4.5 km (15,000 ft)
2. Ensure there are at least six inches of clearance between the sides and back of either the
stand-alone analyzer or the system cabinet.
CAUTIONThe environmental temperature must be 4 °C less than the maximum operating
temperature of the analyzer for every 100 watts dissipated in the cabinet. If the
total power dissipated in the cabinet is >800 watts, then you must provide
forced convection.
9
Installing Yo ur Agilent8703B
Step 6. Meet Electrical Requirements
CAUTIONAlways use the three-prong AC power cord supplied with this product. Failure
to ensure adequate earth grounding by not using this cord may cause product
damage.
WARNINGAny interruption of the protective (grounding) conductor or disconnection
of the protective earth terminal, can result in personal injury, or may
damage the analyzer.
1. Ensure the available AC power source meets the following requirements:
Line Power Requirements
DescriptionMicrowave Test SetLightwave Test Set
Frequency47 Hz to 63 Hz50 Hz to 60 Hz
Voltage at 115 V setting90 V to 132 V90 V to 132 V
Voltage at 230 V setting198 V to 265 V198 V to 265 V
VA/W Maximum450 VA maximum70 W maximum
CAUTIONThe lightwave test set has an autoranging line voltage input, be sure the supply
voltage is within the specified range.
2. Set the line-voltage selector to the position that corresponds to the AC power source, and
verify the correct fuse is installed.
10
Installing Your Agilent8703B
3. Verify that the power cable is not damaged, and that the power-source outlet provides a
protective earth contact. “Available Line Cords” on page 12 shows the available line cords.
11
Installing Yo ur Agilent8703B
Available Line Cords
Plug TypeCable Part No.Plug Description
250V8120-1351
8120-1703
250V8120-1369
Straight *BS1363A
90°
Straight *NZSS198/ASC
90°
8120-0696
250V8120-1689
8120-1692
8120-2857p
125V8120-1378
8120-1521
8120-1992
250V8120-2104
8120-2296
Straight *CEE7-Y11
90°
Straight (Shielded)
Straight *NEMA5-15P
90°
Straight (Medical) UL544
Straight *SEV1011
1959-24507
Type 12 90°
Length
(in/cm)
90/228
90/228
79/200
87/221
79/200
79/200
79/200
90/228
90/228
96/244
79/200
79/200
ColorCountry
Gray
Mint Gray
United Kingdom,
Cyprus, Nigeria,
Zimbabwe,
Singapore
Gray
Australia, New
Zealand
Mint Gray
Mint Gray
Mint Gray
Coco Brown
East and West
Europe, Saudi
Arabia, So. A fr ica,
India (unpolarized in
many nations)
Jade Gray
Jade Gray
Black
United States,
Canada, Mexico,
Philippines,
Taiwan
Mint Gray
Switzerland
Mint Gray
220V8120-2956
8120-2957
250V8120-4211
8120-4600
100V8120-4753
8120-4754
* Part number shown for plug is the industry identifier for the plug only. Number shown for cable is the Agilent
Technologies part number for the complete cable including the plug.
Straight *DHCK107
90°
Straight SABS164
90°
Straight MITI
90°
79/200
79/200
79/200
79/200
90/230
90/230
Mint Gray
Denmark
Mint Gray
Jade GrayRepublic of South
Africa
India
Dark GrayJapan
12
Installing Your Agilent8703B
Step 7. Configuring for Bench Top or Rack Mount Use
There are two kits available for the analyzer:
• Option 908: cabinet flange kit without front handles
• Option 909: cabinet flange kit with front handles
To Attach Cabinet Flanges without Front Handles (Option 908)
1. Ensure that the cabinet f lange kit is complete.
• cabinet mount flanges:
• part number 5063-9212, 88.1 mm high, quantity of 2
• part number 5063-9216, 221.5 mm high, quantity of 2
• screws, quantity of 10
2. Remove the side trim strips.
13
Installing Yo ur Agilent8703B
3. Attach the cabinet flanges to the sides of the front panel. Use three screws for each of the
analyzer top flanges, and use two screws each of the analyzer bottom flanges.
4. Remove the feet and the tilt stands before cabinet mounting the instrument.
14
Installing Your Agilent8703B
To Attach Cabinet Flanges with Front Handles t o the Analyzer (Option 909)
1. Ensure that the cabinet f lange kit with handles is complete.
• cabinet mount flanges with handles:
• part number 5063-9220, 88.1 mm high, quantity of 2
• part number 5063-9332, 221.5 mm high, quantity of 2
• screws, quantity of 10
2. Remove the side trim strips.
15
Installing Yo ur Agilent8703B
3. Attach the cabinet mount flanges and the handles to the sides of the front panel. Use
three screws for each of the analyzer top flange/handles, and use two screws for each of
the analyzer bottom flanges/handle. (Attach the flanges to the outside of the handles.).
4. Remove the feet and the tilt stands before cabinet mounting the instrument.
16
Step 8. Configuring for Printers or Plotters
1. Connect your printer or plotter to the corresponding interface.
Installing Your Agilent8703B
2. If you are using the parallel interface, press
of COPY or GPIO appears.
If you choose:
Local, and toggle PARALLEL, until your choice
• COPY, the parallel port is dedicated for normal copy device use (printers or plotters).
• GPIO, the parallel port is dedicated for general purpose I/O. The analyzer controls the
data input or output through the sequencing capability of the analyzer.
17
Installing Yo ur Agilent8703B
3. Press SET ADDRESSES, and then choose either PRINTER PORT, or PLOTTER PORT, depending
on your printer/plotter device. Or, if you are plotting your files to disk, press
ADDRESSES,
PLOTTER PORT, DISK.
SET
4. Press the key that corresponds to your printer or plotter interface:
(parallel port), or
SERIAL, (serial port).
GPIB PARALLEL,
NOTEThe plotter menu is shown as an example. It will only appear if you select
PLOTTER PORT. Similar interface choices will appear if you select PRINTER PORT.
•If you select GPIB, the GPIB address selection is active. Enter the GPIB address of your
printer or plotter, followed by
x1.
• If you have already selected the PARALLEL [COPY], choice for the parallel-port
configuration, you must also select PARALLEL, in this menu in order to generate a
hardcopy.
18
Installing Your Agilent8703B
5. If you will be using the serial port, adjust the analyzer's baud rate until it is equal to the
baud rate set on the peripheral by pressing
and the
up, and down, front panel keys.
PLOTTER BAUD RATE, or PRINTER BAUD RATE,
NOTEThe plotter menu is shown as an example. It will only appear if you select
PLOTTER PORT.
You can set the analyzer to the following baud rates: 1200, 2400, 4800, 9600, and 19200
6. Also, if you will be using the serial port, you must toggle the transmission control
CNTRL,
(handshaking protocol) until your choice of Xon/Xoff, or DTR/DSR, appears (equal to
XMIT
the transmission control set on the peripheral). The printer menu is shown as an example .
It will only appear if you select
PLOTTER PORT.
NOTETransmission control for plotters is set programmatically.
Xon/Xoff, sets transmission on/transmission off (software handshake).
•
DTR/DSR, sets data terminal ready/data set ready (hardware handshake).
•
19
Installing Yo ur Agilent8703B
7. If you will be creating a plot of the data, toggle PLTR TYPE, until your choice of PLOTTER, or
HPGL PRT, appears.
• Choose
• Choose
8. If you will be using a printer, toggle
PLOTTER, for a pen plotter.
HPGL PRT, for a PCL5 compatible printer.
PRNTR TYPE, until your printer choice appears.
• Choose your printer type from these Hewlett-Packard printers:
•THINKJET
DESKJET (except for HP DeskJet 540 and Deskjet 850C)
•
• LASERJET
•PAINTJET
DJ 540 (for use with HP DeskJet 540 and Deskjet 850C—converts 100 dpi raster
•
information to 300 dpi raster format)
• Choose
EPSON-P2, for Epson-compatible printers (ESC/P2 printer control language).
For a current printer compatibility guide, consult the Webpage at
http://www.agilent.com/find/pcg.
20
Installing Your Agilent8703B
9. Press System,SET CLOCK, to begin setting and activating the time stamp feature so the
analyzer places the time and date on your hardcopies and disk directories.
10.Press each of the following softkeys to set the date and time, followed by
x1.
21
Installing Yo ur Agilent8703B
11.Press ROUND SECONDS, when the time is exactly as you have set it.
22
Installing Your Agilent8703B
Step 9. Perform the Self-Test
NOTEIf the analyzer should fail any of the following tests, call the nearest Agilent
Technologies sales or service office to determine the type of warranty you have.
If repair is necessary, send the analyzer to the nearest Agilent Technologies
service center with a description of any failed test and any error message. Ship
the analyzer using the original packaging materials. Returning the analyzer in
anything other than the original packaging may result in non-warranted
damage.
1. Cycle the AC power using the LINE switch.
2. Watch for the following indications that the analyzer is operating correctly:
23
Installing Yo ur Agilent8703B
Step 10. Configure the Agilent 8703B
• Connect test port cables and optional adapters if you are using other connector types.
• If you are ready to start making measurements, refer to the User’s Guide.
24
Installing Your Agilent8703B
If You Encounter a Problem
If you have difficulty when installing or using the analyzer, check the following list of
commonly encountered problems and troubleshooting procedures. If the problem that you
encounter is not in the following list, contact your nearest Agilent Technologies office for
service, if necessary. A list of Agilent Technologies sales and service offices is provided at the
end of this guide.
Power-Up Problems
If the analyzer display does not light:
1. Check that the power cord is fully seated in both the main power receptacle and the
analyzer power module.
2. Check that the AC line voltage selector switch is in the appropriate position
(230 V/115 V) for your available power supply.
3. Check that the analyzer AC line fuse is not open.
WARNINGFor continued protection against fire hazard, replace the fuse with the same
type and rating.
• Refer to the following graphic to remove the fuse from the power module. You can use a
continuity light or an ohmmeter to check the fuse. An ohmmeter should read very
close to zero ohms if the fuse is good.
• In the microwave test set portion of the analyzer, for 115V operation, use fuse 5A,
125V, UL listed/CSA certified to 248 standard (part number 2110-1059).
• In the microwave test set portion of the analyzer, for 230V operation, use fuse 4A,
250V, built to IEC 127-2/5 standard (part number 2110-1036).
• In the lightwave test set portion of the analyzer, use fuse 3.15 A, 250V, (part number
2110-0957).
25
Installing Yo ur Agilent8703B
If the display lights, but the ventilation fan does not start:
• Check that the fan is not obstructed. To check the fan, follow these steps:
1. Switch the LINE power to the off position.
2. Check that the fan blades are not jammed.
Contact the nearest Agilent Technologies office for service, if necessary. A list of Agilent
Technologies sales and service offices is provided at the end of this guide.
Data Entry Problems
If the data entry controls (keypad, knob, arrow keys) do not respond:
• Check that the ENTRY OFF function is not enabled.
The ENTRY OFF function is enabled after you press the Entry Off key. To return to
normal entry mode, press any function key that has a numeric parameter associated with
it, for example, Start.
• Check that none of the keys are stuck.
• Check that the selected function key accepts data.
For example, Scale Ref accepts data, but System does not.
• Check that the analyzer's "R" GPIB STATUS light is not illuminated.
If the analyzer's "R" GPIB STATUS light is illuminated, a test sequence may be running, or
a connected computer controller may be sending commands or instructions to, or
receiving data from, the analyzer. Press Local if you want to return to LOCAL control.
If the parameter you are trying to enter is not accepted by the analyzer:
• Ensure that you are not attempting to set the parameter greater than or less than its limit.
Refer to the User's Guide for parameter limits.
No RF Output
If there is no RF signal at the front-panel port:
• Check that the signal at the test port is switched on.
1. Press Power and toggle SOURCE PWR to ON.
NOTEIt is possible to set the source power to come from PORT 2 instead of PORT 1,
so you must check the power at the correct port. With factory preset, the power
comes from PORT 1.
• If you are applying external modulation (AM) to the analyzer, check the external
modulating signal or external trigger signals for problems.
26
Installing Your Agilent8703B
CAUTIONIf the error message:
CAUTION: OVERLOAD ON INPUT X, POWER REDUCED
appears on the analyzer display, too much source power is being applied at the
input. In such a case, the input power will need to be reduced before the source
power will remain on.
• If phase-lock error messages appear on the analyzer display, check that the front panel
jumper is secure on the R CHANNEL connectors. If the jumper is secure and the error
messages still appear, contact your nearest Agilent Technologies office for service. A list
of Agilent Technologies sales and service offices is provided at the end of this guide.
27
Agilent Technologies Service Offices
Agilent Technologies Service Offices
Before returning an instrument for service, call the Agilent Technologies Instrument Support
Center at (800) 403-0801, visit the Test and Measurement Web Sites by Country page at
http://www.tm.agilent.com/tmo/country/English/index.html, or call one of the numbers
listed below.
Ship the analyzer using the original packaging materials. Returning the analyzer in anything other than
the original packag ing may result in no n-warranted dama ge. A table listing of Agilent Technologies sales
and service offices is provided at the end of this document