message: NCMesh: support for derefinement for segment elements.
diff: @@ -1701,6 +1701,15 @@ void NCMesh::DerefineElement(int elem)
  ch.node[fv[2]], ch.node[fv[3]])->attribute;
  }
  }
  + else if (el.Geom() == Geometry::SEGMENT)
  + {
  + for (int i = 0; i < 2; i++)
  + {
  + int ni = elements[child[i]].node[i];
  + el.node[i] = ni;
  + fa[i] = faces.Find(ni, ni, ni, ni)->attribute;
  + }
  + }
  else
  {
  MFEM_ABORT("Unsupported element geometry.");
  