gistfile1.txt

<Patch>

<Operation Class="PatchOperationReplace">
  <xpath>//HediffDef[defName = "Heatstroke"]/lethalSeverity</xpath>
  <value>
    <lethalSeverity>0.1</lethalSeverity>
  </value>
</Operation>

<Operation Class="PatchOperationInsert">
  <xpath>//ThingDef[@Name = "StandingLampBase"]/costList/Steel</xpath>
  <order>Append</order>
  <value>
    <Cloth>5</Cloth>
  </value>
</Operation>

<Operation Class="PatchOperationRemove">
  <xpath>//ThingDef[defName = "HospitalBed"]/costList</xpath>
</Operation>

<Operation Class="PatchOperationSequence">
  <success>Always</success>
  <operations>
    <li Class="PatchOperationTest">
      <xpath>//ThingDef[defName = "DiningChair"]/costList</xpath>
      <success>Invert</success>
    </li>
    <li Class="PatchOperationAdd">
      <xpath>//ThingDef[defName = "DiningChair"]</xpath>
      <value>
        <costList />
      </value>
    </li>
  </operations>
</Operation>
<Operation Class="PatchOperationAdd">
  <xpath>//ThingDef[defName = "DiningChair"]/costList</xpath>
  <value>
    <Cloth>5</Cloth>
  </value>
</Operation>

</Patch>

Thank you ;-)