*Heading
 Substructure with CPE3 Elements
*Node
*Element, type=CPE4, elset=one
** Region: (Secn:Picked)
*Elset, elset=I1, generate
** Section: Secn
*Solid Section, elset=I1, material=Elas
1.,
**Nset, nset=Set4,
** 25,
**Nset, nset=Low_Left
** 5,
**
** MATERIALS
**
*Material, name=Elas
*Density
10.,
*Elastic
 1e+08,0.
*step
*frequency,eigen=lanc
2,
*boundary
1,1,2
5,1,2
21,1,2
25,1,2
*node print
u,
*end step
*STEP
*substructure generate, type=z1, overwrite,
recovery matrix=yes, mass matrix=yes,
libr=lib_rbm_solid2d
*RETAINED NODAL DOFS
**,sorted=no
**1003,1,2
*Retained Eigenmodes
*substructure matrix output, stiffness=yes,
mass=yes, recovery=yes, file=lib_rbm_solid2d
*END STEP