This record works together with the control_mesh_generate_truss, control_mesh_generate_beam and control_mesh_generate_trussbeam records.
If switch is set to -yes, the truss or beam of trussbeam will not be connected to the existing nodes, but new nodes will be generated for the generated element.
Afterwards you can typically connect the truss or beam of trussbeam to the existing mesh with constactsprings, so that the end result is that you can model frictional slip between isoparametric elements and structural elements.
See also control_mehs_generate_contactspring.