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  <xs:element id="sionna_PersonnelRelatedExpenseExcludingStockBasedCompensationGeneralAndAdministrativeExpense" abstract="false" name="PersonnelRelatedExpenseExcludingStockBasedCompensationGeneralAndAdministrativeExpense" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sionna_GeneralCorporateAndFacilityExpense" abstract="false" name="GeneralCorporateAndFacilityExpense" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sionna_NumberOfReportableSegmentsNotDisclosedFlag" abstract="false" name="NumberOfReportableSegmentsNotDisclosedFlag" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
</xs:schema>
