A Restriction on Levels () subnode provides the possibility to add a restriction on certain discretization levels. You can add it as a subnode under a Dependent Variable Declaration or Discretization node.

The Allowed space dimensions list puts a restriction on the discretization levels selected in the Levels list. The applicable levels are those defined in the parent node, except for the selected default level. The default level must always be available for all space dimensions.

Adding this node with a restriction on certain levels (for example, the Quintic level for 3D) means that when the physics interface is created for a 3D geometry the Quintic level will not be included.

It is important that excluded levels do not break the sequence for finding lower levels as specified in the Dependent Variable Declaration or Discretization node. Doing so may cause problems for the geometric multigrid solver.