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  <xs:element id="ogs_Fidelity500IndexFundMember" abstract="true" name="Fidelity500IndexFundMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="ogs_FidelityGlobalExU.S.IndexFundMember" abstract="true" name="FidelityGlobalExU.S.IndexFundMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="ogs_FidelityMidCapIndexFundMember" abstract="true" name="FidelityMidCapIndexFundMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="ogs_FidelitySmallCapIndexFundMember" abstract="true" name="FidelitySmallCapIndexFundMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="ogs_JPMorganSmallCapEquityFundClassR5Member" abstract="true" name="JPMorganSmallCapEquityFundClassR5Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="ogs_LoomisSaylesInvestmentGradeBondFundClassAMember" abstract="true" name="LoomisSaylesInvestmentGradeBondFundClassAMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="ogs_ONEGasInc.Member" abstract="true" name="ONEGasInc.Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="ogs_ONEOKInc.Member" abstract="true" name="ONEOKInc.Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
</xs:schema>
