Lenovo D22e-20 User manual

Lenovo
D22e-20,
User Guide

© Copyright Lenovo 2021 i
Product Number
D21215FD0
66D2-KAC6-WW
First Edition (01 2021)
© Copyright Lenovo 2021
All rights reserved.
LENOVO products, data, computer software, and services have been developed exclusively at private expense and are sold to
governmental entities as commercial items as defined by 48 C.F.R. 2.101 with limited and restricted rights to use, reproduction and
disclosure.
LIMITED AND RESTRICTED RIGHTS NOTICE: IF products, data, computer software, or services are delivered pursuant a General
Services Administration "GSA" contract, use, reproduction, or disclosure is subject to restrictions set forth in Contract No. GS-35F-
05925.

ii ©Copyright Lenovo 2021
Contents
Product Number.......................................................................................................................................................................i
Contents ........................................................................................................................................................................ ii
Safety information.................................................................................................................................................................. iii
Safety and Maintenance Guidelines........................................................................................................................................ iv
Chapter 1. Getting started..............................................................................................................................................1-1
Shipping contents ..................................................................................................................................................................... 1-1
Notice for use............................................................................................................................................................................ 1-1
Product overview...................................................................................................................................................................... 1-2
Types of adjustments......................................................................................................................................................... 1-2
User controls...................................................................................................................................................................... 1-2
Cable lock slot.................................................................................................................................................................... 1-2
Setting up your monitor............................................................................................................................................................ 1-3
Connecting and turning on your monitor.......................................................................................................................... 1-3
Registering your option ..................................................................................................................................................... 1-5
Chapter 2. Adjusting and using your monitor..................................................................................................................2-1
Comfort and accessibility.......................................................................................................................................................... 2-1
Arranging your work area ......................................................................................................................................................... 2-1
Positioning and viewing your monitor...................................................................................................................................... 2-1
Quick tips for healthy work habits ............................................................................................................................................ 2-2
Accessibility information ................................................................................................................................................... 2-2
Eye Strain ........................................................................................................................................................................... 2-2
Reduce Flicker.................................................................................................................................................................... 2-2
Low Blue Light.................................................................................................................................................................... 2-3
Accessibility information ................................................................................................................................................... 2-4
Adjusting your monitor image .................................................................................................................................................. 2-5
Using the direct access controls ........................................................................................................................................ 2-5
Using the On-Screen Display (OSD) controls ..................................................................................................................... 2-6
Selecting a supported display mode......................................................................................................................................... 2-9
Understanding power management......................................................................................................................................... 2-9
Caring for your monitor .......................................................................................................................................................... 2-10
Detaching the monitor stand.................................................................................................................................................. 2-10
Wall Mounting (Optional) ....................................................................................................................................................... 2-10
Chapter 3. Reference information ..................................................................................................................................3-1
Monitor specifications .............................................................................................................................................................. 3-1
Troubleshooting........................................................................................................................................................................ 3-2
Manual image setup ................................................................................................................................................................. 3-4
Manually installing the monitor driver .............................................................................................................................. 3-5
Service information ........................................................................................................................................................... 3-7
Appendix A Service and Support ..................................................................................................................................... A-1
Registering your option............................................................................................................................................................. A-1
Online technical support........................................................................................................................................................... A-1
Telephone technical support .................................................................................................................................................... A-1
Appendix B Notices ........................................................................................................................................................ B-1
Recycling information ............................................................................................................................................................... B-2
Collecting and recycling a disused Lenovo computer or monitor...................................................................................... B-2
Disposing of Lenovo computer components ..................................................................................................................... B-2
Trademarks ............................................................................................................................................................................... B-3
Power cords and power adapters ............................................................................................................................................. B-3

© Copyright Lenovo 2021 iii
Safety information
General Safety guidelines
For tips to help you use your computer safety, go to:
http://www.lenovo.com/safety
Before installing this product, read the Safety Information.

iv ©Copyright Lenovo 2021
Safety and Maintenance Guidelines
Important Safety Information
The power cord is designed for use with your monitor. Don’t use a different cord, use only a power source and
connection compatible with this monitor.
WARNING: Always connect your monitor, the computer, and other equipment to a grounded (earthed) power
outlet. To reduce the risk of electric shock or damage to your equipment, do not disable the power cord grounding
feature. The grounding plug is an important safety feature.
WARNING: For your safety, be sure that the grounded power outlet you plug the power cord into is easily
accessible to the operator and located as close to the equipment as possible. To disconnect power from the
equipment, unplug the power cord from the power outlet by grasping the plug firmly. Never pull on the cord.
CAUTION: To protect your monitor, as well as your computer, connect all power cords for your computer and its
peripheral devices (such as a monitor, printer, or scanner) to a surge protection device such as a power strip with
surge protection or uninterruptible power supply (UPS). Not all power strips provide surge protection; the power
strips must be specifically labelled as having this ability. Use a power strip whose manufacturer offers a damage
replacement policy, so you can replace your equipment if surge protection fails.
CAUTION: A certified power supply cord has to be used with this equipment. The relevant national installation
and/or equipment regulations shall be considered. A certified power supply cord not lighter than ordinary
polyvinyl chloride flexible cord according to IEC 60227 (designation H05VV-F 3G 0.75mm² or H05VVH2-F2 3G
0.75mm²) shall be used. An alternative flexible cord is synthetic rubber.
Safety Precautions
■Use only a power source and connection compatible with this monitor, as indicated on the label/back
plate of the monitor.
■Be sure the total ampere rating of the products connected to the outlet does not exceed the current rating of the
electrical outlet, and the total ampere rating of the products connected to the power cord does not exceed the
rating of the power cord. Look on the power label to determine the ampere rating (Amps or A) for each device.
■Install your monitor near a power outlet that you can easily reach. Disconnect the monitor by grasping the plug
firmly and pulling it from the outlet. Never disconnect the monitor by pulling the cord.
■Do not allow anything to rest on the power cord. Do not walk on the cord.
■While using VESA mount application, the AC Inlet must face to down side. Do not face any other position.
Maintenance Guidelines
To enhance the performance and extend the life of your monitor:
■Do not open your monitor cabinet or attempt to service this product yourself. If your monitor is not operating
properly or has been dropped or damaged, contact your Lenovo authorized dealer, reseller, or service provider.
■Adjust only those controls that are described in the operating instructions.
■Turn your monitor off when not in use. You can substantially increase the life expectancy of the monitor by using
a screen saver program and turning off the monitor when not in use.
■Keep your monitor in a well-ventilated area, away from excessive light, heat, or moisture.
■Slots and openings in the cabinet are provided for ventilation. These openings must not be blocked or covered.
Never push objects of any kind into cabinet slots or other openings.
■Unplug the monitor from the power outlet before cleaning. Do not use liquid cleaners or aerosol cleaners.
■Do not drop the monitor or place it on an unstable surface.
■When removing the monitor base, you must lay the monitor face down on a soft area to prevent it from getting
scratched, defaced, or broken.
Cleaning the Monitor
The monitor is a high-quality optical device that requires special care when cleaning. To clean the monitor, follow
these steps:
1. Turn off the computer and the monitor.
2. Unplug your monitor from the power outlet before cleaning.
CAUTION: Do not use benzene, thinner, ammonia, or any volatile substance to clean the monitor screen or cabinet.
These chemicals may damage the monitor. Do not use liquid or aerosol cleaners. Never use water
to clean an LCD screen.
3. Wipe the screen with a dry, soft, clean cloth. If the screen requires additional cleaning, use an antistatic screen
cleaner.
4. Dust the monitor housing. Use a damp cloth to clean the cabinet. If the cabinet requires additional cleaning, use
a clean cloth dampened with isopropyl alcohol.
5. Plug in the monitor.
6. Turn on the monitor and the computer

Chapter 1 Getting started 1-1
Chapter 1. Getting started
This User’s Guide provides detailed operation instructions for the user. For quick instruction overview, please
see the Setup Poster for brief information.
Shipping contents
The product package should include the following items:
Information Flyer
Flat Panel Monitor
Power Cord
HDMI Cable
Monitor Stand
Monitor base
Cable clip
Notice for use
To setup your monitor, please see the illustrations below.
Note: Do not touch the monitor within the screen area. The screen area is glass and can be damaged by
rough handling or excessive pressure.
1. Place your monitor with the screen face down on a soft flat surface.
2. Align the stand assembly bracket to the monitor.
3. Insert the bracket towards monitor until it locks in place.
Note: To attach a VESA mount, please see “Detaching the monitor stand” on page 2-10.

1-2 D22e-20 Flat Panel Monitor User’s Guide
Product overview
This section will provide information on adjusting monitor positions, setting user controls, and using the cable
lock slot.
Types of adjustments
Tilt
Please see the illustration below for an example of the tilt range.
User controls
Your monitor has controls on the front which are used to adjust the display.
For information on how to use these controls, please see “Adjusting your monitor image ” on
page 2-5.
Cable lock slot
Your monitor is equipped with a cable lock slot located on the rear of your monitor. Please
follow the instructions that came with the cable lock to attach it.

Chapter 1 Getting started 1-3
Setting up your monitor
This section provides information to help you set up your monitor.
Connecting and turning on your monitor
Note: Be sure to read the Safety information on page iv before carrying out this procedure.
1. Power off your computer and all attached devices, and unplug the computer power cord.
2. Connect one end of the HDMI cable to the HDMI connector on the back of the computer, and
the other end to the HDMI connector on the monitor. Lenovo recommends that customers
who require to use the HDMI input on their monitor purchase the “Lenovo HDMI to HDMI
cableOB47070”.
For more information, go to the following:
www.lenovo.com/support/monitoraccessories

1-4 D22e-20 Flat Panel Monitor User’s Guide
3. Connect the analog signal cable to the D-SUB connector of the monitor and the other end on
the back of the computer.
4. Plug the monitor power cord and the computer cord into grounded electrical outlets.
Note: A certified power supply cord has to be used with this equipment. The relevant
national installation and/or equipment regulations shall be considered. A certified
power supply cord not lighter than ordinary polyvinyl chloride flexible cord according
to IEC 60227 (designation H05VV-F 3G 0.75mm² or H05VVH2-F2 3G 0.75mm²) shall be
used. Alternative a flexible cord be of synthetic rubber according to IEC 60245
(designation H05RR-F 3G 0.75mm²) shall be used.

Chapter 1 Getting started 1-5
5. Assembled Line Cleaner as shown below.
6. Power on the monitor and the computer.
7. To install the monitor driver, you must download it from Lenovo website
(http://support.lenovo.com/docs/d22e_20) and follow the instructions on page 3-5.
Registering your option
Thank you for purchasing this Lenovo TM product. Please take a few moments to
register your product and provide us with information that will help Lenovo to better
serve you in the future. Your feedback is valuable to us in developing products and
services that are important to you, as well as in developing better ways to communicate
with you. Register your option on the following Web site:
http://www.lenovo.com/register
Lenovo will send you information and updates on your registered product unless you
indicate on the Web site questionnaire that you do not want to receive further
information.

Chapter 2 Adjusting and using your monitor 2-1
Chapter 2. Adjusting and using your monitor
This section will give you information on adjusting and using your monitor.
Comfort and accessibility
Good ergonomic practice is important to get the most from your personal
computer and to avoid discomfort. Arrange your workplace and the
equipment you use to suit your individual needs and the kind of work that you
perform. In addition, use healthy work habits to maximize your performance
and comfort while using your computer.
Arranging your work area
Use a work surface of appropriate height and available working area to allow you to
work in comfort.
Organize you work area to match the way you use materials and equipment. Keep your
work area clean and clear for the materials that you typically use and place the items
that you use most frequently, such as the computer mouse or telephone, within the
easiest reach.
Equipment layout and setup play a large role in your working posture. The following
topics describe how to optimize equipment setup to achieve and maintain good
working posture.
Positioning and viewing your monitor
Position and adjust your computer monitor for comfortable viewing by considering the
following items:
Viewing distance:
Optimal viewing distances for monitors range from approximately 510mm to
760mm (20 in to 30 in) and can vary depending on ambient light and time of day.
You can achieve different viewing distances by repositioning your monitor or by
modifying your posture or chair position. Use a viewing distance that is most
comfortable for you.
Monitor height:
Position the monitor so your head and neck are in a comfortable and neutral
(vertical, or upright) position. If your monitor does not have height adjustments, you
might have to place books or other sturdy objects under the base of the monitor to
achieve the desired height. A general guideline is to position the monitor such that
the top of the screen is at or slightly below your eye-height when you are
comfortably seated. However, be sure to optimize your monitor height so the line of
site between your eyes and the center the monitor suits your preferences for visual
distance and comfortable viewing when your eye muscles are in a relaxed stated.
Tilt :
Adjust the tilt of your monitor to optimize the appearance of the screen content and
to accommodate your preferred head and neck posture.
General location:
Position your monitor to avoid glare or reflections on the screen from overhead
lighting or nearby windows.
The following are some other tips for comfortable viewing of your monitor:
Use adequate lighting for the type of work you are performing.
Use the monitor brightness, contrast, and image adjustment controls, if equipped, to
optimize the image on your screen to meet your visual preferences.
Keep your monitor screen clean so you can focus on the screen’s contents.
Any concentrated and sustained visual activity can be tiring for your eyes. Be sure to
periodically look away from your monitor screen and focus on a far object to allow your
eye muscles to relax. If you have questions on eye fatigue or visual discomfort, consult a
vision care specialist for advice.

2-2 D22e-20 Flat Panel Monitor User’s Guide
Quick tips for healthy work habits
The following information is a summary of some important factors to consider to help
you remain comfortable and productive while you use your computer.
Good posture starts with equipment setup:
The layout of your work area and the setup of your computer equipment have a
large effect on your posture while using your computer. Be sure to optimize the
position and orientation of your equipment by following the tips outlined in
“Arranging your work area ” on page 2-1 so you can maintain a comfortable and
productive posture. Also, be sure to use the adjustment capabilities of your
computer components and office furniture to best suit your preferences now and as
your preferences change over time.
Minor changes in posture can help avoid discomfort:
The longer you sit and work in front of your computer, the more important it is to
observe your working posture. Avoid as summing any one posture for an extended
period of time. Periodically make minor modifications in your posture to help deter
any discomforts that might arise. Make use of any adjustments that your office
furniture or equipment provide to accommodate changes in posture
Short, periodic breaks help ensure healthy computing:
Because computing is primarily a static activity, it is particularly important to take
short breaks from your work. Periodically, stand up in front of your work area,
stretch, walk for a drink of water, or otherwise take a short break from using your
computer. A short break from work gives your body a welcome change in posture
and helps to ensure you remain comfortable and productive while you do work.
Accessibility information
Lenovo is committed to providing greater access to information and technology to
people with disabilities. With assistive technologies, users can access information in the
way most appropriate to their disability. Some of these technologies are already
provided in your operating system; others can be purchased through vendors or
accessed at:
https://lenovo.ssbbartgroup.com/lenovo/request_vpat.php
Eye Strain
Break Times
Computer users should take some time away from the screen especially if working
for prolong hours. Generally, it is recommended to take short breaks (5 – 15 min.)
after 1 –2 hours of continuous computer works. Taking short and frequent breaks is
more advised than longer breaks.
Looking at Distant Objects
Users often blink less when in front of monitor screen. To minimize eye strain and
dryness, users should rest the eye periodically by focusing on objects that are far away.
Eye Exercises
1. Alternate looking up and looking down while keeping the body and head upright.
2. Slowly roll your eyes to look to the left and right.
3. Roll eyes to look at objects on the upper right corner and then on lower right. Do
same thing to look at objects on the upper left and lower left.
Reduce Flicker
Monitor flickers refer to repeated changes in monitor light intensity. It is caused by
several factors including but not limited to voltage fluctuations. Reducing flicker
minimizes eye strain and headaches. ThinkVision monitors allow users to use high
frequency display modes that can effectively reduce flicker.

Chapter 2 Adjusting and using your monitor 2-3
Low Blue Light
Concerns on blue light affecting eye health have risen over the years. Blue light have
wavelength between 300 nm to 500 nm. The monitors have a factory setting that reduces
blue light emissions. Users can enable low blue light mode on these monitors from the
OSD settings.
1. Press to open the main OSD menu.
2.Use or to move among the icons. Select icon (Image color setting) and press
to access this function.

2-4 D22e-20 Flat Panel Monitor User’s Guide
3.Use or move among to the Low blue light item. Press to enable or disable
Low Blue Light.
Accessibility information
Lenovo is committed to providing greater access to information and technology to
people with disabilities. With assistive technologies, users can access information in the
way most appropriate to their disability. Some of these technologies are already
provided in your operating system; others can be purchased through vendors or
accessed at:
https://lenovo.ssbbartgroup.com/lenovo/request_vpat.php

Chapter 2 Adjusting and using your monitor 2-5
Adjusting your monitor image
This section describes the user control features used to adjust your monitor image.
Using the direct access controls
The direct access controls can be used when the On Screen Display (OSD) is not displayed.
Note: The direct access controls are coloured.
Table 2-1. Direct access controls
Icon Control Description
1
Input change
Switches the video input source
Shift back to previous level when in OSD mode.
Exit
Shortcut key for directly opening the menu of source-
selecting while there is no any OSD on the screen.
Press to exit current OSD or return to previous level.
Press and hold for 10 seconds, then the DDC/CI
function will be Enabled/Disabled.
2
Auto Adjustment
Optimizes image (size, position, phase and clock) (For
analog [VGA] source only)
Increase/Up
Up browsing key.
For increasing the value on adjustment bar/tune in.
Press to move to previous item.
3
Brightness
Direct access to Brightness adjustment.
Enable Low Blue
Light
Press and hold for 3 seconds to enable Low Blue Light.
Disable Low Blue
Light
Press and hold for 3 seconds to disable Low Blue Light.
Decrease/Down
Down browsing key.
For decreasing the value on adjustment bar/tune in.
Press to move to next item.
4
Main menu
To access OSD menu.
Press to confirm selection.
Press and hold for 10 seconds will lock menu/un-
lock
menu.
Enter
Press to enter next level on main menu/sub menu
status or enter previous level on adjustment bar.

2-6 D22e-20 Flat Panel Monitor User’s Guide
Using the On-Screen Display (OSD) controls
The settings adjustable with the user controls are viewed through the On-Screen Display
(OSD), as shown below.
To use the controls:
1. Press to open the main OSD menu.
2. Use or to move among the icons. Select an icon and press to access
that function. If there is a sub-menu, you can move between options using
or , then press to select that function. Use or to make
adjustments. Press to save.
3. Press to move backwards through the sub-menus and exit from the OSD.
4. When un-OSD, press and hold for 10 seconds to lock the OSD. This will prevent
accidental adjustments to the OSD. When un-OSD, press and hold for 10 seconds
to unlock the OSD and allow adjustments to the OSD.
5. Enables DDC/CI by default. Use OSD Exit Key, press and hold the buttons for 10
seconds to disable/enable DDC/CI function. The words " DDC/CI
Disable/DDC/CI/Enable" shows on the screen.

Chapter 2 Adjusting and using your monitor 2-7
Table 2-2. OSD functions
OSD Icon on Main Menu Submenu Description
Controls and
Adjustments
Basic image setting
Brightness Adjusts overall brightness.
All input ports
Contrast
Adjusts difference between light
and dark areas.
DCR
Enable dynamic contrast ratio.
Off
On
Display Mode

Standard
Game
Web
Movie
Picture
Scaling Mode
Selects type of scaled image.
Full Screen: expand image to full
screen.
Original AR: same aspect ratio
with input signal.
Over Drive

Off
Normal
Extreme
Automatic Automatically optimizes the image.
Only VGA input port
Clock
Adjusts the number of pixels
scanned by one Horizontal sweep.
Phase
Adjusts the phase of the pixel clock
signal.
Horizontal position Moves the image left or right.
Vertical position Moves the image up or Down.
Image color setting
Preset Mode
Adjusts intensity of red, green, and
blue.
Bluish
Neutral
Reddish
sRGB
All input ports
Custom

Red: Increases or decreases the
saturation of ‘red’ in the image.
Green: Increases or decreases
the saturation of ‘green’ in the
image.
Blue: Increases or decreases the
saturation of ‘blue’ in the image.
Low blue light

Off
On
signal input
VGA
Select analog signal among OSD
controls when you use VGA
connector.
VGA input port
HDMI
Select digital signal among OSD
controls when you use HDMI
connector.
HDMI input port

2-8 D22e-20 Flat Panel Monitor User’s Guide
OSD Icon on Main Menu Submenu Description
Controls and
Adjustments
Menu setting
Information

Model Name:
Refresh:
Firmware
Serial Number:
This Screen does not allow any
changes to the settings.
All input ports
Language
Select OSD Language.
Note: The language chosen only
affects the language of the OSD. It
has no effect on any software
running on the computer.
Menu Horizontal
Changes the horizontal position of
the OSD.
Menu Vertical
Changes the vertical position of the
OSD.
Transparency Choose the transparency of OSD
FreeSync

Off
On Only HDMI input port
OSD Timeout
Sets the length of time the OSD will
remain active after the last time a
button is pressed.
All input ports
Reset All Settings
Resets monitor to the original
factory settings.
Cancel
Factory Reset
All input ports
*Low Blue Light Mode is reducing the blue light content.
*The use of Extreme Mode (response time) may result in reduced display quality when fast moving video graphics
are displayed. Users should check Extreme Mode (response time) to verify if it is compatible with any applications
they would like to use it with.

Chapter 2 Adjusting and using your monitor 2-9
Selecting a supported display mode
The display mode the monitor uses is controlled by the computer. Therefore, refer to your computer
documentation for details on how to change display modes.
The image size, position and shape might change when the display mode changes. This is normal and the image
can be readjusted using automatic image setup and the image controls.
Unlike CRT monitors, which require a high refresh rate to minimize flicker, LCD or Flat Panel technology is
inherently flicker-free.
Note: If your system has previously been used with a CRT monitor and is currently configured to a display
mode outside the range of this monitor, you may need to re-attach the CRT monitor temporarily until you have
re-configured the system; preferably to 1920x1080 at 60Hz, which is the Native Resolution Display mode.
The display modes shown below have been optimized at the factory.
Table 2-3.Factory set display modes
Timing
Refresh rate(Hz)
PAL
50Hz
640x480
60Hz,67Hz, 72Hz,75Hz
720x400
70Hz
800x600
56Hz,60Hz,72Hz,75Hz
832x624
75Hz
1024x768
60Hz,70Hz,75Hz
1152x864
75Hz
1280x1024
60Hz,70Hz,75Hz
1440x900
reduced 60Hz
1600x900
60Hz,75Hz
1680x1050
60Hz, reduced 60Hz
1920x1080
60Hz,75Hz
Understanding power management
Power management is invoked when the computer recognizes that you have not using your mouse or keyboard for a
user-definable period. There are several states as described in the table below.
For optimal performance, switch off your monitor at the end of each working day, or whenever you expect to leave it
unused for long periods during the day.
Table2-4.Power indicator
State Power Indicator Screen Restoring Operation Compliance
On Steady White Normal
Standby/
Suspend Steady amber Blank
Press a key or move the mouse. There may be a slight
delay reappears.
Note: Standby also occurs if there is no image output
to the monitor.
Off Off Off Press power key to switch on There may be a slight
delay before the image reappears.
** Maximum power consumption with max luminance.
This document is informational only and reflects laboratory performance. Your product may perform differently,
depending on the software, components and peripherals you ordered and shall have no obligation to update such
information. Accordingly, the customer should not rely upon this information in making decisions about electrical
tolerances or otherwise. No warranty as to accuracy or completeness is expressed or implied.

2-10 D22e-20 Flat Panel Monitor User’s Guide
Caring for your monitor
Be sure to turn off the power before you perform any maintenance on the monitor.
Do not:
Apply water or liquid directly to your monitor.
Use solvents or abrasives.
Use flammable cleaning materials to clean your monitor or any other electrical
equipment.
Touch the screen area of your monitor with sharp or abrasive items. This type of contact
may cause permanent damage to your screen.
Use any cleaner which contains an anti-static solution or similar additives. This may
harm the coating of the screen area.
Do:
Lightly dampen a soft cloth with water and use this to gently wipe the covers and the
screen.
Remove grease or finger marks with a damp cloth and a little mild detergent.
Detaching the monitor stand
After placing the monitor face down on a clean surface or soft cloth, Loosen the screws,
Remove the stand and base from the monitor.
Wall Mounting (Optional)
Refer to the instructions that come with the VESA compatible base mounting kit.
1. Place the monitor face down on a non-abrasive surface on stable flat table.
2. Remove the stand.
3. Attach the mounting bracket from the wall mounting kit to the monitor.
4. Mount the monitor on the wall by following the instructions that come with the
base mounting kit.
NOTE: For use only with UL and GS Listed Wall Mount Bracket with minimum
weight/load bearing capacity of 8.00 kg. In order to fulfil TCO Certification for this wall
mounting option, shielded power cable is mandatory to be used.