This update applies to the following:

  • ​Windows 10, version 1607 for x86-based systems

  • Windows 10, version 1607 for x64-based systems

  • Windows Server 2016

  • Windows Server 2016 (Server Core installation)

Summary

This update makes quality improvements to the servicing stack, which is the component that installs Windows updates. Servicing stack updates (SSU) makes sure that you have a robust and reliable servicing stack so that your devices can receive and install Microsoft updates.

How to get this update

Method 1: Windows Update 

This update is available through Windows Update. It will be downloaded and installed automatically.  

Method 2: Microsoft Update Catalog 

To get the stand-alone package for this update, go to the Microsoft Update Catalog website.

Method 3: Windows Server Update Services

This update is also available through Windows Server Update Services (WSUS).

Prerequisites 

There are no prerequisites to apply this update.

Restart information 

You don't have to restart your computer after you apply this update.

Removal information

Servicing stack updates (SSUs) make changes to how updates are installed and cannot be uninstalled from the device.

Update replacement information 

This update replaces the previously released update KB5001402.

File Information

The English (United States) version of this software update installs files that have the attributes that are listed in the following tables.

File name

File version

Date

Time

File size

luainstall.dll

10.0.14393.4222

13-Jan-2021

20:50

51,464

appxreg.dll

10.0.14393.4222

13-Jan-2021

20:51

36,624

appxprovisionpackage.dll

10.0.14393.4222

13-Jan-2021

21:10

77,592

EventsInstaller.dll

10.0.14393.4222

13-Jan-2021

21:10

176,888

CntrtextInstaller.dll

10.0.14393.4222

13-Jan-2021

20:50

140,040

grouptrusteeai.dll

10.0.14393.4222

13-Jan-2021

20:55

38,664

sppinst.dll

10.0.14393.4222

13-Jan-2021

20:51

37,144

timezoneai.dll

10.0.14393.4222

13-Jan-2021

20:50

59,656

httpai.dll

10.0.14393.4222

13-Jan-2021

20:50

27,896

cmifw.dll

10.0.14393.4222

13-Jan-2021

20:50

90,376

FirewallOfflineAPI.dll

10.0.14393.4222

13-Jan-2021

20:51

161,544

NetSetupAI.dll

10.0.14393.4222

13-Jan-2021

20:50

104,200

NetSetupApi.dll

10.0.14393.4222

13-Jan-2021

20:51

111,896

NetSetupEngine.dll

10.0.14393.4645

23-Aug-2021

21:06

606,480

ImplatSetup.dll

10.0.14393.4222

13-Jan-2021

21:10

101,144

winsockai.dll

10.0.14393.4222

13-Jan-2021

20:51

73,464

ws2_helper.dll

10.0.14393.0

15-Jul-2016

18:33

70,144

wmicmiplugin.dll

10.0.14393.4222

13-Jan-2021

20:50

273,144

offlinelsa.dll

10.0.14393.0

15-Jul-2016

18:27

102,400

offlinesam.dll

10.0.14393.4645

23-Aug-2021

21:26

226,552

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

4:06

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

4:06

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

4:05

3,072

poqexec.exe.mui

10.0.14393.0

15-Dec-2020

17:24

3,072

poqexec.exe.mui

10.0.14393.0

14-Dec-2020

15:46

3,072

poqexec.exe.mui

10.0.14393.0

29-Jun-2020

18:07

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

4:04

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

4:01

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

4:08

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

4:08

3,072

poqexec.exe.mui

10.0.14393.0

27-Dec-2020

11:19

3,072

poqexec.exe.mui

10.0.14393.0

16-Dec-2020

9:29

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

4:05

3,072

poqexec.exe.mui

10.0.14393.0

16-Mar-2020

13:26

3,072

poqexec.exe.mui

10.0.14393.0

25-Jun-2020

22:33

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

4:05

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

4:05

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

4:06

3,072

poqexec.exe.mui

10.0.14393.0

25-Apr-2020

15:59

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

4:07

3,072

poqexec.exe.mui

10.0.14393.0

25-Dec-2020

13:23

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

4:07

3,072

mofinstall.dll

10.0.14393.4222

13-Jan-2021

20:51

72,456

esscli.dll

10.0.14393.4222

13-Jan-2021

20:51

299,784

mofd.dll

10.0.14393.4222

13-Jan-2021

20:51

207,640

repdrvfs.dll

10.0.14393.4645

23-Aug-2021

21:06

282,896

fastprox.dll

10.0.14393.4222

13-Jan-2021

20:51

669,960

wbemcomn.dll

10.0.14393.4645

23-Aug-2021

21:06

388,376

wbemcore.dll

10.0.14393.4645

23-Aug-2021

21:07

984,344

wmiutils.dll

10.0.14393.4222

13-Jan-2021

20:51

98,568

wbemprox.dll

10.0.14393.4222

13-Jan-2021

20:51

36,616

shtransform.dll

10.0.14393.4222

13-Jan-2021

21:10

33,016

bfsvc.dll

10.0.14393.4645

23-Aug-2021

21:06

167,704

securebootai.dll

10.0.14393.4645

23-Aug-2021

21:06

31,000

fveupdateai.dll

10.0.14393.4222

13-Jan-2021

20:50

27,912

cmitrust.dll

10.0.14393.4222

13-Jan-2021

20:50

275,720

peerdistai.dll

10.0.14393.4222

13-Jan-2021

20:47

32,520

PrintAdvancedInstaller.dll

10.0.14393.4222

13-Jan-2021

20:47

93,448

msdtcadvancedinstaller.dll

10.0.14393.4222

13-Jan-2021

20:47

55,048

netfxconfig.dll

10.0.14393.4222

13-Jan-2021

20:47

27,400

ConfigureIEOptionalComponentsAI.dll

10.0.14393.4222

13-Jan-2021

20:47

46,856

IEFileInstallAI.dll

10.0.14393.4222

13-Jan-2021

20:47

35,592

servicemodelregai.dll

10.0.14393.4222

13-Jan-2021

20:47

72,968

SetIEInstalledDateAI.dll

10.0.14393.4222

13-Jan-2021

20:47

22,792

bcdeditai.dll

10.0.14393.4222

13-Jan-2021

20:51

272,136

FeatureSettingsOverride.dll

10.0.14393.4222

13-Jan-2021

21:11

34,552

SupplementalServicingAI.dll

10.0.14393.4222

13-Jan-2021

20:36

17,920

PrimitiveTransformers.dll

10.0.14393.4222

13-Jan-2021

21:10

51,480

AriTransformer.dll

10.0.14393.4222

13-Jan-2021

21:10

49,944

WpnDataTransformer.dll

10.0.14393.4222

13-Jan-2021

21:10

30,488

mqcmiplugin.dll

5.0.1.1

13-Jan-2021

20:50

130,824

iissetupai.dll

10.0.14393.4222

13-Jan-2021

21:10

98,552

cleanupai.dll

10.0.14393.4222

13-Jan-2021

20:50

21,752

wdscore.dll

10.0.14393.4222

13-Jan-2021

20:55

219,928

drvstore.dll

10.0.14393.4222

13-Jan-2021

20:51

750,344

dpx.dll

5.0.1.1

23-Aug-2021

21:06

381,208

msdelta.dll

5.0.1.1

13-Jan-2021

20:51

406,776

mspatcha.dll

5.0.1.1

13-Jan-2021

20:50

44,808

cmiaisupport.dll

10.0.14393.4222

13-Jan-2021

20:50

1,914,120

WcmTypes.xsd

Not versioned

25-May-2016

11:04

1,047

CbsMsg.dll

10.0.14393.0

15-Jul-2016

18:57

49,504

CbsCore.dll

10.0.14393.4645

23-Aug-2021

21:26

1,788,168

TiWorker.exe

10.0.14393.4222

13-Jan-2021

20:32

197,120

TiFileFetcher.exe

10.0.14393.4645

23-Aug-2021

21:06

246,536

drupdate.dll

10.0.14393.4222

13-Jan-2021

20:50

285,960

wcp.dll

10.0.14393.4645

23-Aug-2021

21:26

2,736,392

cmiadapter.dll

10.0.14393.4222

13-Jan-2021

20:50

72,968

smiengine.dll

10.0.14393.4645

23-Aug-2021

21:06

747,272

smipi.dll

10.0.14393.4222

13-Jan-2021

20:50

31,992

poqexec.exe

10.0.14393.4222

13-Jan-2021

20:32

120,320

x86_installed

Not versioned

25-May-2016

10:59

9

GlobalInstallOrder.xml

Not versioned

14-May-2020

3:00

1,247,706

wrpint.dll

10.0.14393.4222

13-Jan-2021

20:51

66,824

File name

File version

Date

Time

File size

luainstall.dll

10.0.14393.4222

13-Jan-2021

21:11

60,176

appxreg.dll

10.0.14393.4222

13-Jan-2021

21:10

42,776

appxprovisionpackage.dll

10.0.14393.4222

13-Jan-2021

21:20

86,800

EventsInstaller.dll

10.0.14393.4222

13-Jan-2021

21:20

222,488

CntrtextInstaller.dll

10.0.14393.4222

13-Jan-2021

21:11

163,088

grouptrusteeai.dll

10.0.14393.4222

13-Jan-2021

21:15

43,792

sppinst.dll

10.0.14393.4222

13-Jan-2021

21:11

42,248

timezoneai.dll

10.0.14393.4222

13-Jan-2021

21:11

70,392

httpai.dll

10.0.14393.4222

13-Jan-2021

21:11

30,968

cmifw.dll

10.0.14393.4222

13-Jan-2021

21:11

101,624

FirewallOfflineAPI.dll

10.0.14393.4222

13-Jan-2021

21:11

184,568

NetSetupAI.dll

10.0.14393.4222

13-Jan-2021

21:10

132,344

NetSetupApi.dll

10.0.14393.4222

13-Jan-2021

21:10

148,760

NetSetupEngine.dll

10.0.14393.4645

24-Aug-2021

2:30

858,376

ImplatSetup.dll

10.0.14393.4222

13-Jan-2021

21:20

135,960

winsockai.dll

10.0.14393.4222

13-Jan-2021

21:11

82,200

ws2_helper.dll

10.0.14393.0

15-Jul-2016

19:20

86,016

wmicmiplugin.dll

10.0.14393.4222

13-Jan-2021

21:10

394,512

offlinelsa.dll

10.0.14393.0

15-Jul-2016

19:11

114,688

offlinesam.dll

10.0.14393.4645

24-Aug-2021

2:43

253,176

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

7:37

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

7:30

3,072

poqexec.exe.mui

10.0.14393.0

15-Dec-2020

17:24

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

7:30

3,072

poqexec.exe.mui

10.0.14393.0

14-Dec-2020

18:03

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

7:31

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

7:36

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

7:31

3,072

poqexec.exe.mui

10.0.14393.0

12-Jan-2021

16:58

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

7:29

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

7:33

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

7:41

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

7:36

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

7:37

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

7:31

3,072

poqexec.exe.mui

10.0.14393.0

14-Dec-2020

16:44

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

7:31

3,072

poqexec.exe.mui

10.0.14393.0

25-Oct-2020

17:44

3,072

poqexec.exe.mui

10.0.14393.0

7-Jan-2020

12:36

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

7:40

3,072

poqexec.exe.mui

10.0.14393.0

17-Dec-2020

3:20

3,072

poqexec.exe.mui

10.0.14393.0

16-Jul-2016

7:33

3,072

mofinstall.dll

10.0.14393.4222

13-Jan-2021

21:11

73,496

esscli.dll

10.0.14393.4222

13-Jan-2021

21:11

397,592

mofd.dll

10.0.14393.4222

13-Jan-2021

21:11

246,024

repdrvfs.dll

10.0.14393.4645

24-Aug-2021

2:31

353,032

fastprox.dll

10.0.14393.4222

13-Jan-2021

21:12

855,304

wbemcomn.dll

10.0.14393.4645

24-Aug-2021

2:31

451,848

wbemcore.dll

10.0.14393.4645

24-Aug-2021

2:31

1,229,576

wmiutils.dll

10.0.14393.4222

13-Jan-2021

21:11

119,032

wbemprox.dll

10.0.14393.4222

13-Jan-2021

21:11

42,760

shtransform.dll

10.0.14393.4222

13-Jan-2021

21:20

38,680

bfsvc.dll

10.0.14393.4645

24-Aug-2021

2:30

195,336

securebootai.dll

10.0.14393.4645

24-Aug-2021

2:30

33,544

fveupdateai.dll

10.0.14393.4222

13-Jan-2021

21:11

32,504

cmitrust.dll

10.0.14393.4222

13-Jan-2021

21:11

400,120

peerdistai.dll

10.0.14393.4222

13-Jan-2021

21:08

38,136

PrintAdvancedInstaller.dll

10.0.14393.4222

13-Jan-2021

21:08

102,648

msdtcadvancedinstaller.dll

10.0.14393.4222

13-Jan-2021

21:08

64,760

netfxconfig.dll

10.0.14393.4222

13-Jan-2021

21:08

30,456

ConfigureIEOptionalComponentsAI.dll

10.0.14393.4222

13-Jan-2021

21:08

53,496

IEFileInstallAI.dll

10.0.14393.4222

13-Jan-2021

21:09

37,128

servicemodelregai.dll

10.0.14393.4222

13-Jan-2021

21:08

88,312

SetIEInstalledDateAI.dll

10.0.14393.4222

13-Jan-2021

21:08

24,312

bcdeditai.dll

10.0.14393.4222

13-Jan-2021

21:11

296,208

FeatureSettingsOverride.dll

10.0.14393.4222

13-Jan-2021

21:20

40,216

SupplementalServicingAI.dll

10.0.14393.4222

13-Jan-2021

20:33

18,432

PrimitiveTransformers.dll

10.0.14393.4222

13-Jan-2021

21:20

65,808

AriTransformer.dll

10.0.14393.4222

13-Jan-2021

21:20

56,592

WpnDataTransformer.dll

10.0.14393.4222

13-Jan-2021

21:20

37,136

mqcmiplugin.dll

5.0.1.1

13-Jan-2021

21:10

154,392

appserverai.dll

10.0.14393.4222

13-Jan-2021

21:10

113,944

RDWebAI.dll

10.0.14393.4222

13-Jan-2021

21:10

119,568

tssdisai.dll

10.0.14393.4222

13-Jan-2021

21:10

121,616

VmHostAI.dll

10.0.14393.4222

13-Jan-2021

21:10

100,112

iissetupai.dll

10.0.14393.4222

13-Jan-2021

21:20

122,648

cleanupai.dll

10.0.14393.4222

13-Jan-2021

21:11

23,832

wdscore.dll

10.0.14393.4222

13-Jan-2021

21:15

267,000

drvstore.dll

10.0.14393.4222

13-Jan-2021

21:11

908,560

dpx.dll

5.0.1.1

24-Aug-2021

2:30

507,144

msdelta.dll

5.0.1.1

13-Jan-2021

21:11

514,840

mspatcha.dll

5.0.1.1

13-Jan-2021

21:11

54,040

cmiaisupport.dll

10.0.14393.4645

24-Aug-2021

2:30

2,923,784

WcmTypes.xsd

Not versioned

25-May-2016

14:34

1,047

CbsMsg.dll

10.0.14393.0

15-Jul-2016

19:56

50,528

CbsCore.dll

10.0.14393.4645

24-Aug-2021

2:44

2,039,064

TiWorker.exe

10.0.14393.4222

13-Jan-2021

20:29

199,680

TiFileFetcher.exe

10.0.14393.4645

24-Aug-2021

2:31

289,032

drupdate.dll

10.0.14393.4222

13-Jan-2021

21:11

336,120

wcp.dll

10.0.14393.4645

24-Aug-2021

2:43

3,199,736

cmiadapter.dll

10.0.14393.4222

13-Jan-2021

21:11

84,728

smiengine.dll

10.0.14393.4645

24-Aug-2021

2:31

864,520

smipi.dll

10.0.14393.0

15-Jul-2016

19:11

28,160

poqexec.exe

10.0.14393.4222

13-Jan-2021

20:28

142,848

amd64_installed

Not versioned

25-May-2016

14:30

9

GlobalInstallOrder.xml

Not versioned

12-Oct-2020

22:35

1,247,706

wrpint.dll

10.0.14393.4222

13-Jan-2021

21:11

76,568

luainstall.dll

10.0.14393.4222

13-Jan-2021

20:50

51,464

appxreg.dll

10.0.14393.4222

13-Jan-2021

20:51

36,624

appxprovisionpackage.dll

10.0.14393.4222

13-Jan-2021

21:10

77,592

EventsInstaller.dll

10.0.14393.4222

13-Jan-2021

21:10

176,888

CntrtextInstaller.dll

10.0.14393.4222

13-Jan-2021

20:50

140,040

grouptrusteeai.dll

10.0.14393.4222

13-Jan-2021

20:55

38,664

sppinst.dll

10.0.14393.4222

13-Jan-2021

20:51

37,144

timezoneai.dll

10.0.14393.4222

13-Jan-2021

20:50

59,656

httpai.dll

10.0.14393.4222

13-Jan-2021

20:50

27,896

cmifw.dll

10.0.14393.4222

13-Jan-2021

20:50

90,376

FirewallOfflineAPI.dll

10.0.14393.4222

13-Jan-2021

20:51

161,544

NetSetupAI.dll

10.0.14393.4222

13-Jan-2021

20:50

104,200

NetSetupApi.dll

10.0.14393.4222

13-Jan-2021

20:51

111,896

NetSetupEngine.dll

10.0.14393.4645

23-Aug-2021

21:06

606,480

ImplatSetup.dll

10.0.14393.4222

13-Jan-2021

21:10

101,144

winsockai.dll

10.0.14393.4222

13-Jan-2021

20:51

73,464

ws2_helper.dll

10.0.14393.0

15-Jul-2016

18:33

70,144

wmicmiplugin.dll

10.0.14393.4222

13-Jan-2021

20:50

273,144

mofinstall.dll

10.0.14393.4222

13-Jan-2021

20:51

72,456

esscli.dll

10.0.14393.4222

13-Jan-2021

20:51

299,784

mofd.dll

10.0.14393.4222

13-Jan-2021

20:51

207,640

repdrvfs.dll

10.0.14393.4645

23-Aug-2021

21:06

282,896

fastprox.dll

10.0.14393.4222

13-Jan-2021

20:51

669,960

wbemcomn.dll

10.0.14393.4645

23-Aug-2021

21:06

388,376

wbemcore.dll

10.0.14393.4645

23-Aug-2021

21:07

984,344

wmiutils.dll

10.0.14393.4222

13-Jan-2021

20:51

98,568

wbemprox.dll

10.0.14393.4222

13-Jan-2021

20:51

36,616

shtransform.dll

10.0.14393.4222

13-Jan-2021

21:10

33,016

bfsvc.dll

10.0.14393.4645

23-Aug-2021

21:06

167,704

securebootai.dll

10.0.14393.4645

23-Aug-2021

21:06

31,000

fveupdateai.dll

10.0.14393.4222

13-Jan-2021

20:50

27,912

cmitrust.dll

10.0.14393.4222

13-Jan-2021

20:50

275,720

peerdistai.dll

10.0.14393.4222

13-Jan-2021

20:47

32,520

PrintAdvancedInstaller.dll

10.0.14393.4222

13-Jan-2021

20:47

93,448

msdtcadvancedinstaller.dll

10.0.14393.4222

13-Jan-2021

20:47

55,048

netfxconfig.dll

10.0.14393.4222

13-Jan-2021

20:47

27,400

ConfigureIEOptionalComponentsAI.dll

10.0.14393.4222

13-Jan-2021

20:47

46,856

IEFileInstallAI.dll

10.0.14393.4222

13-Jan-2021

20:47

35,592

servicemodelregai.dll

10.0.14393.4222

13-Jan-2021

20:47

72,968

SetIEInstalledDateAI.dll

10.0.14393.4222

13-Jan-2021

20:47

22,792

bcdeditai.dll

10.0.14393.4222

13-Jan-2021

20:51

272,136

FeatureSettingsOverride.dll

10.0.14393.4222

13-Jan-2021

21:11

34,552

SupplementalServicingAI.dll

10.0.14393.4222

13-Jan-2021

20:36

17,920

PrimitiveTransformers.dll

10.0.14393.4222

13-Jan-2021

21:10

51,480

AriTransformer.dll

10.0.14393.4222

13-Jan-2021

21:10

49,944

WpnDataTransformer.dll

10.0.14393.4222

13-Jan-2021

21:10

30,488

appserverai.dll

10.0.14393.4222

13-Jan-2021

20:49

93,456

RDWebAI.dll

10.0.14393.4222

13-Jan-2021

20:50

103,696

tssdisai.dll

10.0.14393.4222

13-Jan-2021

20:49

102,168

VmHostAI.dll

10.0.14393.4222

13-Jan-2021

20:50

83,216

cleanupai.dll

10.0.14393.4222

13-Jan-2021

20:50

21,752

wdscore.dll

10.0.14393.4222

13-Jan-2021

20:55

219,928

drvstore.dll

10.0.14393.4222

13-Jan-2021

20:51

750,344

dpx.dll

5.0.1.1

23-Aug-2021

21:06

381,208

msdelta.dll

5.0.1.1

13-Jan-2021

20:51

406,776

mspatcha.dll

5.0.1.1

13-Jan-2021

20:50

44,808

cmiaisupport.dll

10.0.14393.4222

13-Jan-2021

20:50

1,914,120

WcmTypes.xsd

Not versioned

25-May-2016

11:04

1,047

CbsMsg.dll

10.0.14393.0

15-Jul-2016

18:57

49,504

CbsCore.dll

10.0.14393.4645

23-Aug-2021

21:26

1,788,168

TiWorker.exe

10.0.14393.4222

13-Jan-2021

20:32

197,120

TiFileFetcher.exe

10.0.14393.4645

23-Aug-2021

21:06

246,536

drupdate.dll

10.0.14393.4222

13-Jan-2021

20:50

285,960

wcp.dll

10.0.14393.4645

23-Aug-2021

21:26

2,736,392

cmiadapter.dll

10.0.14393.4222

13-Jan-2021

20:50

72,968

smiengine.dll

10.0.14393.4645

23-Aug-2021

21:06

747,272

smipi.dll

10.0.14393.4222

13-Jan-2021

20:50

31,992

poqexec.exe

10.0.14393.4222

13-Jan-2021

20:32

120,320

x86_installed

Not versioned

25-May-2016

10:59

9

GlobalInstallOrder.xml

Not versioned

14-May-2020

3:00

1,247,706

wrpint.dll

10.0.14393.4222

13-Jan-2021

20:51

66,824

References

For information about SSUs, see the following articles:

For more information about Dynamic Updates, see the following articles:

Learn about the terminology that Microsoft uses to describe software updates.

Need more help?

Want more options?

Explore subscription benefits, browse training courses, learn how to secure your device, and more.

Communities help you ask and answer questions, give feedback, and hear from experts with rich knowledge.