anchor.diff:  ! This subroutine calculates elemetal internal forces
   !------------------------------------------------------------
   
  -   REAL(ReKi),     INTENT(IN   ):: Nuu0(:) ! Nodal initial position for each element !bjj: not used
      REAL(ReKi),     INTENT(IN   ):: Nuuu(:) ! Nodal displacement of Mass 1 for each element
  -   REAL(ReKi),     INTENT(IN   ):: Nrr0(:) ! Nodal rotation parameters for initial position !bjj: not used
      REAL(ReKi),     INTENT(IN   ):: Nrrr(:) ! Nodal rotation parameters for displacement of Mass 1
      REAL(ReKi),     INTENT(IN   ):: Nvvv(:) ! Nodal velocity of Mass 1: m/s for each element
      REAL(ReKi),     INTENT(IN   ):: EStif0_GL(:,:,:) ! Nodal material properties for each element
  
positive.code: 
  END SUBROUTINE BD_ElementMatrixForce
  !-----------------------------------------------------------------------------------------------------------------------------------
  SUBROUTINE BD_GenerateDynamicElementForce(uuN0,rrN0,uuN,vvN,aaN,     &
                                            Stif0,Mass0,gravity,u,&
                                            damp_flag,beta,       &
                                            elem_total,node_elem,dof_node,ngp,&
                                            quadrature,gw,hhx,hpx,Jaco,uu0,E10,&
  
negative.code: END SUBROUTINE BD_ElasticForce
  !-----------------------------------------------------------------------------------------------------------------------------------
  SUBROUTINE BD_GaussPointDataMass(hhx,hpx,Jaco,Nvvv,Naaa,RR0,node_elem,dof_node,&
                                   vvv,aaa,vvp,mEta,rho,ErrStat,ErrMsg)
  !------------------------------------------------------------------
  ! This subroutine calculates the mass quantities at the Gauss point
  ! 1) velocity; 2) acceleration; 3) derivative of velocity wrt axis
  