 <OpenGeoSysProjectDiff base_file="element_deactivation_M_3D.prj">

   <add sel=".//processes/process">

     <constitutive_relation id="0">

       <type>LinearElasticIsotropic</type>

       <youngs_modulus>E</youngs_modulus>

       <poissons_ratio>nu</poissons_ratio>

     </constitutive_relation>

   </add>

 </OpenGeoSysProjectDiff>