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    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInAccountsAndNotesReceivable_C80AC5C07A786A31A01AD2231CDAD2E2" xlink:to="lab_us-gaap_IncreaseDecreaseInAccountsAndNotesReceivable_C80AC5C07A786A31A01AD2231CDAD2E2" xlink:type="arc" />
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    <link:label id="lab_us-gaap_IncreaseDecreaseInOtherOperatingAssets_F901701F0871544205BBD2231CDA7BF0_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInOtherOperatingAssets_F901701F0871544205BBD2231CDA7BF0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Increase (Decrease) in Other Operating Assets</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInAccruedLiabilities" xlink:label="loc_us-gaap_IncreaseDecreaseInAccruedLiabilities_7090ACCC72D9BD54093FD2231CDB7A3D" xlink:type="locator" />
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    <link:label id="lab_us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable_EB8DB3BCD951E1C16966D2231CDB9A07_terseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable_EB8DB3BCD951E1C16966D2231CDB9A07" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Increase in income taxes</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable" xlink:label="loc_us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable_EB8DB3BCD951E1C16966D2231CDB9A07" xlink:type="locator" />
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    <link:label id="lab_us-gaap_IncreaseDecreaseInPensionAndPostretirementObligations_A003D641C42A8F0783EFD2231CDBB3D0_terseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInPensionAndPostretirementObligations_A003D641C42A8F0783EFD2231CDBB3D0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Increase in deferred pension and postretirement benefits</link:label>
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    <link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_15AF147C4105D56ED2F8D220EA98AFE7_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_15AF147C4105D56ED2F8D220EA98AFE7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Exercisable at end of period</link:label>
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    <link:loc xlink:href="nx-20191031.xsd#nx_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract" xlink:label="loc_nx_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract_5A9153ED2DD3BEFAC4D0D220EA9842CA" xlink:type="locator" />
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    <link:label id="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_459B99BEC3D9043BEDB4D220EA9880D6_terseLabel_en-US" xlink:label="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_459B99BEC3D9043BEDB4D220EA9880D6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Outstanding at end of period</link:label>
    <link:label id="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_459B99BEC3D9043BEDB4D220EA9880D6_label_en-US" xlink:label="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_459B99BEC3D9043BEDB4D220EA9880D6" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term</link:label>
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    <link:label id="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_2515B232D5421CB5BBD4D220EA985933_label_en-US" xlink:label="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_2515B232D5421CB5BBD4D220EA985933" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term</link:label>
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    <link:label id="lab_us-gaap_PropertyPlantAndEquipmentGross_CB5FDE432FD0495283AA90E9206669A2_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentGross_CB5FDE432FD0495283AA90E9206669A2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Property, Plant and Equipment, Gross</link:label>
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    <link:label id="lab_us-gaap_Depreciation_63FA5E531AEFF2EC6B0F90E920674FFF_label_en-US" xlink:label="lab_us-gaap_Depreciation_63FA5E531AEFF2EC6B0F90E920674FFF" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Depreciation</link:label>
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    <link:label id="lab_nx_A2018CreditFacilityMember_F59B21453358D7C91F819381CA210B44_terseLabel_en-US" xlink:label="lab_nx_A2018CreditFacilityMember_F59B21453358D7C91F819381CA210B44" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Credit Agreement</link:label>
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    <link:label id="lab_nx_LessThanOneandOneHalfLeverageRatioMember_F419D13D7E378697B78D9381CA31DBE6_terseLabel_en-US" xlink:label="lab_nx_LessThanOneandOneHalfLeverageRatioMember_F419D13D7E378697B78D9381CA31DBE6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Less than or equal to 1.50 to 1.00</link:label>
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    <link:label id="lab_nx_BetweenOneandOneHalfandTwoandOneQuarterLeverageRatioMember_A66F3BF73415DCBCE1DB9381CA3199F4_terseLabel_en-US" xlink:label="lab_nx_BetweenOneandOneHalfandTwoandOneQuarterLeverageRatioMember_A66F3BF73415DCBCE1DB9381CA3199F4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Greater than 1.50 to 1.00, but less than or equal to 2.25 to 1.00</link:label>
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    <link:label id="lab_nx_BetweenOneandOneHalfandTwoandOneQuarterLeverageRatioMember_A66F3BF73415DCBCE1DB9381CA3199F4_documentation_en-US" xlink:label="lab_nx_BetweenOneandOneHalfandTwoandOneQuarterLeverageRatioMember_A66F3BF73415DCBCE1DB9381CA3199F4" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Between One and One Half and Two and One Quarter Leverage Ratio</link:label>
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    <link:label id="lab_nx_BetweenTwoandOneQuarterandThreeLeverageRatioMember_4425265F29F11CEE46D89381CA315266_terseLabel_en-US" xlink:label="lab_nx_BetweenTwoandOneQuarterandThreeLeverageRatioMember_4425265F29F11CEE46D89381CA315266" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Greater than 2.25 to 1.00, but less than or equal to 3.00 to 1.00</link:label>
    <link:label id="lab_nx_BetweenTwoandOneQuarterandThreeLeverageRatioMember_4425265F29F11CEE46D89381CA315266_label_en-US" xlink:label="lab_nx_BetweenTwoandOneQuarterandThreeLeverageRatioMember_4425265F29F11CEE46D89381CA315266" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Between Two and One Quarter and Three Leverage Ratio [Member]</link:label>
    <link:label id="lab_nx_BetweenTwoandOneQuarterandThreeLeverageRatioMember_4425265F29F11CEE46D89381CA315266_documentation_en-US" xlink:label="lab_nx_BetweenTwoandOneQuarterandThreeLeverageRatioMember_4425265F29F11CEE46D89381CA315266" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Between Two and One Quarter and Three Leverage Ratio [Member]</link:label>
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    <link:label id="lab_nx_GreaterThanThreeLeverageRatioMember_B355091B20BDA909119B9381CA31606E_terseLabel_en-US" xlink:label="lab_nx_GreaterThanThreeLeverageRatioMember_B355091B20BDA909119B9381CA31606E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Greater than 3.00 to 1.00</link:label>
    <link:loc xlink:href="nx-20191031.xsd#nx_GreaterThanThreeLeverageRatioMember" xlink:label="loc_nx_GreaterThanThreeLeverageRatioMember_B355091B20BDA909119B9381CA31606E" xlink:type="locator" />
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    <link:label id="lab_us-gaap_LondonInterbankOfferedRateLIBORMember_AAE7BA6C478C5AED01C09381CA315090_terseLabel_en-US" xlink:label="lab_us-gaap_LondonInterbankOfferedRateLIBORMember_AAE7BA6C478C5AED01C09381CA315090" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">LIBOR Rate Loans</link:label>
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    <link:label id="lab_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_AFFBAAC69F689EC2D9A9D755CAED5997_terseLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_AFFBAAC69F689EC2D9A9D755CAED5997" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Defined Benefit Plan, Plan Assets, Category [Axis]</link:label>
    <link:label id="lab_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_AFFBAAC69F689EC2D9A9D755CAED5997_label_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_AFFBAAC69F689EC2D9A9D755CAED5997" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Defined Benefit Plan, Plan Assets, Category [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" xlink:label="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_AFFBAAC69F689EC2D9A9D755CAED5997" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_AFFBAAC69F689EC2D9A9D755CAED5997" xlink:to="lab_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_AFFBAAC69F689EC2D9A9D755CAED5997" xlink:type="arc" />
    <link:label id="lab_us-gaap_PlanAssetCategoriesDomain_CE82CED133B0E4F5F706D755CAEDE87C_terseLabel_en-US" xlink:label="lab_us-gaap_PlanAssetCategoriesDomain_CE82CED133B0E4F5F706D755CAEDE87C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Defined Benefit Plan, Plan Assets, Category [Domain]</link:label>
    <link:label id="lab_us-gaap_PlanAssetCategoriesDomain_CE82CED133B0E4F5F706D755CAEDE87C_label_en-US" xlink:label="lab_us-gaap_PlanAssetCategoriesDomain_CE82CED133B0E4F5F706D755CAEDE87C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Defined Benefit Plan, Plan Assets, Category [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanAssetCategoriesDomain" xlink:label="loc_us-gaap_PlanAssetCategoriesDomain_CE82CED133B0E4F5F706D755CAEDE87C" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_CE82CED133B0E4F5F706D755CAEDE87C" xlink:to="lab_us-gaap_PlanAssetCategoriesDomain_CE82CED133B0E4F5F706D755CAEDE87C" xlink:type="arc" />
    <link:label id="lab_us-gaap_MoneyMarketFundsMember_C1E20585A8FE6DF28205D755CAEE7BCB_terseLabel_en-US" xlink:label="lab_us-gaap_MoneyMarketFundsMember_C1E20585A8FE6DF28205D755CAEE7BCB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Money market fund</link:label>
    <link:label id="lab_us-gaap_MoneyMarketFundsMember_C1E20585A8FE6DF28205D755CAEE7BCB_label_en-US" xlink:label="lab_us-gaap_MoneyMarketFundsMember_C1E20585A8FE6DF28205D755CAEE7BCB" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Money Market Funds [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MoneyMarketFundsMember" xlink:label="loc_us-gaap_MoneyMarketFundsMember_C1E20585A8FE6DF28205D755CAEE7BCB" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_MoneyMarketFundsMember_C1E20585A8FE6DF28205D755CAEE7BCB" xlink:to="lab_us-gaap_MoneyMarketFundsMember_C1E20585A8FE6DF28205D755CAEE7BCB" xlink:type="arc" />
    <link:label id="lab_us-gaap_EquityFundsMember_234AA45E6666D721A46ED755CAEE7038_terseLabel_en-US" xlink:label="lab_us-gaap_EquityFundsMember_234AA45E6666D721A46ED755CAEE7038" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Equity securities</link:label>
    <link:label id="lab_us-gaap_EquityFundsMember_234AA45E6666D721A46ED755CAEE7038_label_en-US" xlink:label="lab_us-gaap_EquityFundsMember_234AA45E6666D721A46ED755CAEE7038" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Equity Funds [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityFundsMember" xlink:label="loc_us-gaap_EquityFundsMember_234AA45E6666D721A46ED755CAEE7038" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EquityFundsMember_234AA45E6666D721A46ED755CAEE7038" xlink:to="lab_us-gaap_EquityFundsMember_234AA45E6666D721A46ED755CAEE7038" xlink:type="arc" />
    <link:label id="lab_nx_LargeCapitalizationMember_F22B51180D9C1C11B189D755CAEEAE46_terseLabel_en-US" xlink:label="lab_nx_LargeCapitalizationMember_F22B51180D9C1C11B189D755CAEEAE46" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Large capitalization</link:label>
    <link:label id="lab_nx_LargeCapitalizationMember_F22B51180D9C1C11B189D755CAEEAE46_label_en-US" xlink:label="lab_nx_LargeCapitalizationMember_F22B51180D9C1C11B189D755CAEEAE46" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Large Capitalization [Member]</link:label>
    <link:label id="lab_nx_LargeCapitalizationMember_F22B51180D9C1C11B189D755CAEEAE46_documentation_en-US" xlink:label="lab_nx_LargeCapitalizationMember_F22B51180D9C1C11B189D755CAEEAE46" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">This category includes information about ownership interests mutual funds that contains large capitalization stocks.</link:label>
    <link:loc xlink:href="nx-20191031.xsd#nx_LargeCapitalizationMember" xlink:label="loc_nx_LargeCapitalizationMember_F22B51180D9C1C11B189D755CAEEAE46" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_nx_LargeCapitalizationMember_F22B51180D9C1C11B189D755CAEEAE46" xlink:to="lab_nx_LargeCapitalizationMember_F22B51180D9C1C11B189D755CAEEAE46" xlink:type="arc" />
    <link:label id="lab_nx_SmallcapitilizationMember_7C190CF885963B108A20D755CAEEF3D7_terseLabel_en-US" xlink:label="lab_nx_SmallcapitilizationMember_7C190CF885963B108A20D755CAEEF3D7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Small capitalization</link:label>
    <link:label id="lab_nx_SmallcapitilizationMember_7C190CF885963B108A20D755CAEEF3D7_label_en-US" xlink:label="lab_nx_SmallcapitilizationMember_7C190CF885963B108A20D755CAEEF3D7" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Small capitilization [Member]</link:label>
    <link:label id="lab_nx_SmallcapitilizationMember_7C190CF885963B108A20D755CAEEF3D7_documentation_en-US" xlink:label="lab_nx_SmallcapitilizationMember_7C190CF885963B108A20D755CAEEF3D7" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">This category includes information about ownership interests mutual funds that contains small capitalization stocks.</link:label>
    <link:loc xlink:href="nx-20191031.xsd#nx_SmallcapitilizationMember" xlink:label="loc_nx_SmallcapitilizationMember_7C190CF885963B108A20D755CAEEF3D7" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_nx_SmallcapitilizationMember_7C190CF885963B108A20D755CAEEF3D7" xlink:to="lab_nx_SmallcapitilizationMember_7C190CF885963B108A20D755CAEEF3D7" xlink:type="arc" />
    <link:label id="lab_nx_InternationalEquityMember_4544F5AFC3FC7155A174D755CAEEC5E6_terseLabel_en-US" xlink:label="lab_nx_InternationalEquityMember_4544F5AFC3FC7155A174D755CAEEC5E6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">International equity</link:label>
    <link:label id="lab_nx_InternationalEquityMember_4544F5AFC3FC7155A174D755CAEEC5E6_label_en-US" xlink:label="lab_nx_InternationalEquityMember_4544F5AFC3FC7155A174D755CAEEC5E6" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">International Equity [Member]</link:label>
    <link:label id="lab_nx_InternationalEquityMember_4544F5AFC3FC7155A174D755CAEEC5E6_documentation_en-US" xlink:label="lab_nx_InternationalEquityMember_4544F5AFC3FC7155A174D755CAEEC5E6" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">This category includes information about ownership interests mutual funds that contains international company stocks.</link:label>
    <link:loc xlink:href="nx-20191031.xsd#nx_InternationalEquityMember" xlink:label="loc_nx_InternationalEquityMember_4544F5AFC3FC7155A174D755CAEEC5E6" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_nx_InternationalEquityMember_4544F5AFC3FC7155A174D755CAEEC5E6" xlink:to="lab_nx_InternationalEquityMember_4544F5AFC3FC7155A174D755CAEEC5E6" xlink:type="arc" />
    <link:label id="lab_nx_OtherAssetCategoryMember_6FB9B854ED4F4DDF1E7CD755CAEF27DD_terseLabel_en-US" xlink:label="lab_nx_OtherAssetCategoryMember_6FB9B854ED4F4DDF1E7CD755CAEF27DD" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Other</link:label>
    <link:label id="lab_nx_OtherAssetCategoryMember_6FB9B854ED4F4DDF1E7CD755CAEF27DD_label_en-US" xlink:label="lab_nx_OtherAssetCategoryMember_6FB9B854ED4F4DDF1E7CD755CAEF27DD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Other Asset Category [Member]</link:label>
    <link:label id="lab_nx_OtherAssetCategoryMember_6FB9B854ED4F4DDF1E7CD755CAEF27DD_documentation_en-US" xlink:label="lab_nx_OtherAssetCategoryMember_6FB9B854ED4F4DDF1E7CD755CAEF27DD" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Other Asset Category [Member]</link:label>
    <link:loc xlink:href="nx-20191031.xsd#nx_OtherAssetCategoryMember" xlink:label="loc_nx_OtherAssetCategoryMember_6FB9B854ED4F4DDF1E7CD755CAEF27DD" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_nx_OtherAssetCategoryMember_6FB9B854ED4F4DDF1E7CD755CAEF27DD" xlink:to="lab_nx_OtherAssetCategoryMember_6FB9B854ED4F4DDF1E7CD755CAEF27DD" xlink:type="arc" />
    <link:label id="lab_us-gaap_FixedIncomeFundsMember_23693B0CFAD385C1A4EFD755CAEFD13C_terseLabel_en-US" xlink:label="lab_us-gaap_FixedIncomeFundsMember_23693B0CFAD385C1A4EFD755CAEFD13C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Fixed income</link:label>
    <link:label id="lab_us-gaap_FixedIncomeFundsMember_23693B0CFAD385C1A4EFD755CAEFD13C_label_en-US" xlink:label="lab_us-gaap_FixedIncomeFundsMember_23693B0CFAD385C1A4EFD755CAEFD13C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Fixed Income Funds [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FixedIncomeFundsMember" xlink:label="loc_us-gaap_FixedIncomeFundsMember_23693B0CFAD385C1A4EFD755CAEFD13C" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FixedIncomeFundsMember_23693B0CFAD385C1A4EFD755CAEFD13C" xlink:to="lab_us-gaap_FixedIncomeFundsMember_23693B0CFAD385C1A4EFD755CAEFD13C" xlink:type="arc" />
    <link:label id="lab_nx_HighqualitycorebondMember_25116F51B449BA59B07DD755CAEF6DD4_terseLabel_en-US" xlink:label="lab_nx_HighqualitycorebondMember_25116F51B449BA59B07DD755CAEF6DD4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">High-quality core bond</link:label>
    <link:label id="lab_nx_HighqualitycorebondMember_25116F51B449BA59B07DD755CAEF6DD4_label_en-US" xlink:label="lab_nx_HighqualitycorebondMember_25116F51B449BA59B07DD755CAEF6DD4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">High quality core bond [Member]</link:label>
    <link:label id="lab_nx_HighqualitycorebondMember_25116F51B449BA59B07DD755CAEF6DD4_documentation_en-US" xlink:label="lab_nx_HighqualitycorebondMember_25116F51B449BA59B07DD755CAEF6DD4" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Mutual fund investment in a fudn that is composed of a variety of bonds that are in combination designed to provide a safe bond investment.</link:label>
    <link:loc xlink:href="nx-20191031.xsd#nx_HighqualitycorebondMember" xlink:label="loc_nx_HighqualitycorebondMember_25116F51B449BA59B07DD755CAEF6DD4" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_nx_HighqualitycorebondMember_25116F51B449BA59B07DD755CAEF6DD4" xlink:to="lab_nx_HighqualitycorebondMember_25116F51B449BA59B07DD755CAEF6DD4" xlink:type="arc" />
    <link:label id="lab_us-gaap_USTreasuryAndGovernmentMember_492AEF3D93893329033AD755CAEFAFA1_terseLabel_en-US" xlink:label="lab_us-gaap_USTreasuryAndGovernmentMember_492AEF3D93893329033AD755CAEFAFA1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">High-quality government bond</link:label>
    <link:label id="lab_us-gaap_USTreasuryAndGovernmentMember_492AEF3D93893329033AD755CAEFAFA1_label_en-US" xlink:label="lab_us-gaap_USTreasuryAndGovernmentMember_492AEF3D93893329033AD755CAEFAFA1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">US Treasury and Government [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_USTreasuryAndGovernmentMember" xlink:label="loc_us-gaap_USTreasuryAndGovernmentMember_492AEF3D93893329033AD755CAEFAFA1" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_USTreasuryAndGovernmentMember_492AEF3D93893329033AD755CAEFAFA1" xlink:to="lab_us-gaap_USTreasuryAndGovernmentMember_492AEF3D93893329033AD755CAEFAFA1" xlink:type="arc" />
    <link:label id="lab_nx_HighyieldbondMember_E1BC742707A3196A54D6D755CAEF9D9F_terseLabel_en-US" xlink:label="lab_nx_HighyieldbondMember_E1BC742707A3196A54D6D755CAEF9D9F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">High-yield bond</link:label>
    <link:label id="lab_nx_HighyieldbondMember_E1BC742707A3196A54D6D755CAEF9D9F_label_en-US" xlink:label="lab_nx_HighyieldbondMember_E1BC742707A3196A54D6D755CAEF9D9F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">High yield bond [Member]</link:label>
    <link:label id="lab_nx_HighyieldbondMember_E1BC742707A3196A54D6D755CAEF9D9F_documentation_en-US" xlink:label="lab_nx_HighyieldbondMember_E1BC742707A3196A54D6D755CAEF9D9F" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Mutual fund interest in a diversified portfolio of bonds are rated below investment grade.</link:label>
    <link:loc xlink:href="nx-20191031.xsd#nx_HighyieldbondMember" xlink:label="loc_nx_HighyieldbondMember_E1BC742707A3196A54D6D755CAEF9D9F" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_nx_HighyieldbondMember_E1BC742707A3196A54D6D755CAEF9D9F" xlink:to="lab_nx_HighyieldbondMember_E1BC742707A3196A54D6D755CAEF9D9F" xlink:type="arc" />
    <link:label id="lab_us-gaap_DefinedBenefitPlanDisclosureLineItems_270AC2B6BF887C864C74D755CAF0CEC7_terseLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanDisclosureLineItems_270AC2B6BF887C864C74D755CAF0CEC7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Defined Benefit Plan Disclosure [Line Items]</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_270AC2B6BF887C864C74D755CAF0CEC7" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_270AC2B6BF887C864C74D755CAF0CEC7" xlink:to="lab_us-gaap_DefinedBenefitPlanDisclosureLineItems_270AC2B6BF887C864C74D755CAF0CEC7" xlink:type="arc" />
    <link:label id="lab_nx_DefinedBenefitPlanEmployerContributionPercentageMatchOfCompensation_2EB3CD0D9269FFD06C99D755CAF0759F_terseLabel_en-US" xlink:label="lab_nx_DefinedBenefitPlanEmployerContributionPercentageMatchOfCompensation_2EB3CD0D9269FFD06C99D755CAF0759F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Employer contribution percentage match of compensation</link:label>
    <link:label id="lab_nx_DefinedBenefitPlanEmployerContributionPercentageMatchOfCompensation_2EB3CD0D9269FFD06C99D755CAF0759F_label_en-US" xlink:label="lab_nx_DefinedBenefitPlanEmployerContributionPercentageMatchOfCompensation_2EB3CD0D9269FFD06C99D755CAF0759F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Defined Benefit Plan Employer Contribution Percentage Match Of Compensation</link:label>
    <link:label id="lab_nx_DefinedBenefitPlanEmployerContributionPercentageMatchOfCompensation_2EB3CD0D9269FFD06C99D755CAF0759F_documentation_en-US" xlink:label="lab_nx_DefinedBenefitPlanEmployerContributionPercentageMatchOfCompensation_2EB3CD0D9269FFD06C99D755CAF0759F" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Defined Benefit Plan, Employer Contribution, Percentage Match of Compensation</link:label>
    <link:loc xlink:href="nx-20191031.xsd#nx_DefinedBenefitPlanEmployerContributionPercentageMatchOfCompensation" xlink:label="loc_nx_DefinedBenefitPlanEmployerContributionPercentageMatchOfCompensation_2EB3CD0D9269FFD06C99D755CAF0759F" xlink:type="locator" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_C6FDD157255FF636DD7AD755CAFBBE4A" xlink:type="locator" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProductWarrantyAccrualPayments" xlink:label="loc_us-gaap_ProductWarrantyAccrualPayments_C55F7E73C4C0C6BEE5CC90E91FDA4076" xlink:type="locator" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyReceivableProceeds" xlink:label="loc_us-gaap_LossContingencyReceivableProceeds_00691EDC8E4FB56A644190E91FDB3E8B" xlink:type="locator" />
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    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent_F1ED340332F691D68FC090E91FDBB08B_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent_F1ED340332F691D68FC090E91FDBB08B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2016</link:label>
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    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears_D665FA0DBD5F34BD0FAC90E91FDC011B_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears_D665FA0DBD5F34BD0FAC90E91FDC011B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2019</link:label>
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    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears_AFB8ACD268D6E58355D490E91FDC969C_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears_AFB8ACD268D6E58355D490E91FDC969C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2020</link:label>
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