 <OpenGeoSysProjectDiff base_file="cube_1e0.prj">

   <replace after_includes="true" sel=".//time_loop/output/prefix/text()">1e0_{:meshname}_upper</replace>

   <add after_includes="true" sel=".//linear_solvers/linear_solver/eigen">

     <triangular_matrix>Upper</triangular_matrix>

   </add>

 </OpenGeoSysProjectDiff>