Answer:
FE mesh refinements can also be found in the Data navigator in RFEM 6 under "Types for Nodes", "Types for Lines", "Types for Surfaces", and "Types for Solids".
Depending on the type of the FE mesh refinement, you can define nodal mesh refinements, line mesh refinements, surface mesh refinements, and solid mesh refinements.
The respective parameters have to be defined in the corresponding dialog box (for example, "New Nodal Mesh Refinement"); see the image.
You can create several mesh refinements at the same time in the list on the left. You can also use/assign the mesh refinement at a later point in time.