diff --git a/base/internals/psi_bld_tmphalo.f90 b/base/internals/psi_bld_tmphalo.f90
index b31707ca..97e28489 100644
--- a/base/internals/psi_bld_tmphalo.f90
+++ b/base/internals/psi_bld_tmphalo.f90
@@ -44,105 +44,110 @@
 !    desc     - type(psb_desc_type).    The communication descriptor.        
 !    info     - integer.                  return code.
 !
-subroutine psi_bld_tmphalo(desc,info)
-  use psb_desc_mod
-  use psb_serial_mod
-  use psb_const_mod
-  use psb_error_mod
-  use psb_penv_mod
-  use psb_realloc_mod
-  use psi_mod, psb_protect_name => psi_bld_tmphalo
-  implicit none
-  type(psb_desc_type), intent(inout) :: desc
-  integer(psb_ipk_), intent(out) :: info
-
-  integer(psb_ipk_),allocatable :: helem(:),hproc(:)
-  integer(psb_ipk_),allocatable :: tmphl(:)
-
-  integer(psb_ipk_) ::  i,j,np,me,lhalo,nhalo,&
-       & n_col, err_act,  key, ih, nh, idx, nk,icomm
-  integer(psb_ipk_) :: ictxt,n_row
-  character(len=20)   :: name,ch_err
-
-  info = psb_success_
-  name = 'psi_bld_tmphalo'
-  call psb_erractionsave(err_act)
-
-  ictxt = desc%get_context()
-  icomm = desc%get_mpic()
-  n_row = desc%get_local_rows()
-  n_col = desc%get_local_cols()
-
-  ! check on blacs grid 
-  call psb_info(ictxt, me, np)
-  if (np == -1) then
-    info = psb_err_context_error_
-    call psb_errpush(info,name)
-    goto 9999
-  endif
-
-  if (.not.(desc%is_bld())) then 
-    info = psb_err_invalid_cd_state_
-    call psb_errpush(info,name)
-    goto 9999
-  end if
-
-  ! Here we do not know yet who owns what, so we have 
-  ! to call fnd_owner.
-  nh = (n_col-n_row)
-  Allocate(helem(max(1,nh)),stat=info)
-  if (info /= psb_success_) then 
-    call psb_errpush(psb_err_from_subroutine_,name,a_err='Allocate')
-    goto 9999      
-  end if
-
-  do i=1, nh
-    helem(i) = n_row+i ! desc%loc_to_glob(n_row+i)
-  end do
-
-  call desc%indxmap%l2gip(helem(1:nh),info)
-  call desc%indxmap%fnd_owner(helem(1:nh),hproc,info)
-      
-  if (info /= psb_success_) then 
-    call psb_errpush(psb_err_from_subroutine_,name,a_err='fnd_owner')
-    goto 9999      
-  endif
-  if (nh > size(hproc)) then 
-    info=psb_err_from_subroutine_
-    call psb_errpush(psb_err_from_subroutine_,name,a_err='nh > size(hproc)')
-    goto 9999      
-  end if
-
-  allocate(tmphl((3*((n_col-n_row)+1)+1)),stat=info)
-  if (info /= psb_success_) then 
-    call psb_errpush(psb_err_from_subroutine_,name,a_err='Allocate')
-    goto 9999      
-  end if
-  j  = 1
-  do i=1,nh
-    tmphl(j+0) = hproc(i)
-    if (tmphl(j+0)<0) then 
-      write(psb_err_unit,*) me,'Unrecoverable error: missing proc from asb',&
-           & i, nh, n_row+i,helem(i),hproc(i)      
+submodule (psi_i_mod) psi_bld_tmphalo_impl_mod
+
+contains
+
+  subroutine psi_bld_tmphalo(desc,info)
+    use psb_desc_mod
+    use psb_serial_mod
+    use psb_const_mod
+    use psb_error_mod
+    use psb_penv_mod
+    use psb_realloc_mod
+    implicit none
+    type(psb_desc_type), intent(inout) :: desc
+    integer(psb_ipk_), intent(out) :: info
+
+    integer(psb_ipk_),allocatable :: helem(:),hproc(:)
+    integer(psb_ipk_),allocatable :: tmphl(:)
+
+    integer(psb_ipk_) ::  i,j,np,me,lhalo,nhalo,&
+         & n_col, err_act,  key, ih, nh, idx, nk,icomm
+    integer(psb_ipk_) :: ictxt,n_row
+    character(len=20)   :: name,ch_err
+
+    info = psb_success_
+    name = 'psi_bld_tmphalo'
+    call psb_erractionsave(err_act)
+
+    ictxt = desc%get_context()
+    icomm = desc%get_mpic()
+    n_row = desc%get_local_rows()
+    n_col = desc%get_local_cols()
+
+    ! check on blacs grid 
+    call psb_info(ictxt, me, np)
+    if (np == -1) then
+      info = psb_err_context_error_
+      call psb_errpush(info,name)
+      goto 9999
+    endif
+
+    if (.not.(desc%is_bld())) then 
       info = psb_err_invalid_cd_state_
       call psb_errpush(info,name)
       goto 9999
     end if
-    tmphl(j+1) = 1
-    tmphl(j+2) = n_row+i
-    j          = j + 3
-  end do
-  tmphl(j) = -1
-  lhalo = j
-  nhalo = (lhalo-1)/3
 
-  call psb_move_alloc(tmphl,desc%halo_index,info)
+    ! Here we do not know yet who owns what, so we have 
+    ! to call fnd_owner.
+    nh = (n_col-n_row)
+    Allocate(helem(max(1,nh)),stat=info)
+    if (info /= psb_success_) then 
+      call psb_errpush(psb_err_from_subroutine_,name,a_err='Allocate')
+      goto 9999      
+    end if
+
+    do i=1, nh
+      helem(i) = n_row+i ! desc%loc_to_glob(n_row+i)
+    end do
+
+    call desc%indxmap%l2gip(helem(1:nh),info)
+    call desc%indxmap%fnd_owner(helem(1:nh),hproc,info)
+
+    if (info /= psb_success_) then 
+      call psb_errpush(psb_err_from_subroutine_,name,a_err='fnd_owner')
+      goto 9999      
+    endif
+    if (nh > size(hproc)) then 
+      info=psb_err_from_subroutine_
+      call psb_errpush(psb_err_from_subroutine_,name,a_err='nh > size(hproc)')
+      goto 9999      
+    end if
 
-  call psb_erractionrestore(err_act)
-  return
+    allocate(tmphl((3*((n_col-n_row)+1)+1)),stat=info)
+    if (info /= psb_success_) then 
+      call psb_errpush(psb_err_from_subroutine_,name,a_err='Allocate')
+      goto 9999      
+    end if
+    j  = 1
+    do i=1,nh
+      tmphl(j+0) = hproc(i)
+      if (tmphl(j+0)<0) then 
+        write(psb_err_unit,*) me,'Unrecoverable error: missing proc from asb',&
+             & i, nh, n_row+i,helem(i),hproc(i)      
+        info = psb_err_invalid_cd_state_
+        call psb_errpush(info,name)
+        goto 9999
+      end if
+      tmphl(j+1) = 1
+      tmphl(j+2) = n_row+i
+      j          = j + 3
+    end do
+    tmphl(j) = -1
+    lhalo = j
+    nhalo = (lhalo-1)/3
+
+    call psb_move_alloc(tmphl,desc%halo_index,info)
+
+    call psb_erractionrestore(err_act)
+    return
 
 9999 call psb_error_handler(ictxt,err_act)
 
     return
 
-end subroutine psi_bld_tmphalo
+  end subroutine psi_bld_tmphalo
+
+end submodule psi_bld_tmphalo_impl_mod
diff --git a/base/internals/psi_bld_tmpovrl.f90 b/base/internals/psi_bld_tmpovrl.f90
index 5423c51f..a6740002 100644
--- a/base/internals/psi_bld_tmpovrl.f90
+++ b/base/internals/psi_bld_tmpovrl.f90
@@ -50,101 +50,105 @@
 !    desc     - type(psb_desc_type).  The communication descriptor.        
 !    info     - integer.              return code.
 !
-subroutine psi_bld_tmpovrl(iv,desc,info)
-  use psb_desc_mod
-  use psb_serial_mod
-  use psb_const_mod
-  use psb_error_mod
-  use psb_penv_mod
-  use psb_realloc_mod
-  use psi_mod, psb_protect_name => psi_bld_tmpovrl
-  implicit none
-  integer(psb_ipk_), intent(in)  :: iv(:)
-  type(psb_desc_type), intent(inout) :: desc
-  integer(psb_ipk_), intent(out)  :: info
-
-  !locals
-  integer(psb_ipk_) :: counter,i,j,np,me,loc_row,err,loc_col,nprocs,&
-       & l_ov_ix,l_ov_el,idx, err_act, itmpov, k, glx, icomm
-  integer(psb_ipk_), allocatable  :: ov_idx(:),ov_el(:,:)
-
-  integer(psb_ipk_) :: ictxt,n_row, debug_unit, debug_level
-  character(len=20)   :: name,ch_err
-
-  info = psb_success_
-  name = 'psi_bld_tmpovrl'
-  call psb_erractionsave(err_act)
-  debug_unit  = psb_get_debug_unit()
-  debug_level = psb_get_debug_level()
-  ictxt = desc%get_context()
-  icomm = desc%get_mpic()
-
-  ! check on blacs grid 
-  call psb_info(ictxt, me, np)
-  if (np == -1) then
-    info = psb_err_context_error_
-    call psb_errpush(info,name)
-    goto 9999
-  endif
-
-  l_ov_ix=0
-  l_ov_el=0
-  i = 1
-  do while (iv(i) /= -1) 
-    idx = iv(i)
-    i       = i + 1
-    nprocs  = iv(i)
-    i       = i + 1
-    l_ov_ix = l_ov_ix+3*(nprocs-1)
-    l_ov_el = l_ov_el + 1
-    i       = i + nprocs     
-  enddo
-
-  l_ov_ix = l_ov_ix+3  
-
-  if (debug_level >= psb_debug_inner_) &
-       & write(debug_unit,*) me,' ',trim(name),': Ov len',l_ov_ix,l_ov_el
-
-  allocate(ov_idx(l_ov_ix),ov_el(l_ov_el,3), stat=info)
-  if (info /= psb_no_err_) then
-    info=psb_err_from_subroutine_
-    err=info
-    call psb_errpush(err,name,a_err='psb_realloc')
-    goto 9999
-  end if
-
-  l_ov_ix=0
-  l_ov_el=0
-  i = 1
-  do while (iv(i) /= -1) 
-    idx = iv(i)
-    i   = i+1
-    nprocs = iv(i)
-    l_ov_el          = l_ov_el+1
-    ov_el(l_ov_el,1) = idx                    ! Index
-    ov_el(l_ov_el,2) = nprocs                 ! How many procs
-    ov_el(l_ov_el,3) = minval(iv(i+1:i+nprocs))  ! master proc
-    do j=1, nprocs
-      if (iv(i+j) /= me) then
-        ov_idx(l_ov_ix+1) = iv(i+j)
-        ov_idx(l_ov_ix+2) = 1
-        ov_idx(l_ov_ix+3) = idx
-        l_ov_ix = l_ov_ix+3
-      endif
+submodule (psi_i_mod) psi_bld_tmpovrl_impl_mod
+
+contains
+  subroutine psi_bld_tmpovrl(iv,desc,info)
+    use psb_desc_mod
+    use psb_serial_mod
+    use psb_const_mod
+    use psb_error_mod
+    use psb_penv_mod
+    use psb_realloc_mod
+    implicit none
+    integer(psb_ipk_), intent(in)  :: iv(:)
+    type(psb_desc_type), intent(inout) :: desc
+    integer(psb_ipk_), intent(out)  :: info
+
+    !locals
+    integer(psb_ipk_) :: counter,i,j,np,me,loc_row,err,loc_col,nprocs,&
+         & l_ov_ix,l_ov_el,idx, err_act, itmpov, k, glx, icomm
+    integer(psb_ipk_), allocatable  :: ov_idx(:),ov_el(:,:)
+
+    integer(psb_ipk_) :: ictxt,n_row, debug_unit, debug_level
+    character(len=20)   :: name,ch_err
+
+    info = psb_success_
+    name = 'psi_bld_tmpovrl'
+    call psb_erractionsave(err_act)
+    debug_unit  = psb_get_debug_unit()
+    debug_level = psb_get_debug_level()
+    ictxt = desc%get_context()
+    icomm = desc%get_mpic()
+
+    ! check on blacs grid 
+    call psb_info(ictxt, me, np)
+    if (np == -1) then
+      info = psb_err_context_error_
+      call psb_errpush(info,name)
+      goto 9999
+    endif
+
+    l_ov_ix=0
+    l_ov_el=0
+    i = 1
+    do while (iv(i) /= -1) 
+      idx = iv(i)
+      i       = i + 1
+      nprocs  = iv(i)
+      i       = i + 1
+      l_ov_ix = l_ov_ix+3*(nprocs-1)
+      l_ov_el = l_ov_el + 1
+      i       = i + nprocs     
     enddo
-    i = i + nprocs + 1
-  enddo
-  l_ov_ix         = l_ov_ix + 1
-  ov_idx(l_ov_ix) = -1
-  call psb_move_alloc(ov_idx,desc%ovrlap_index,info) 
-  if (info == psb_success_) call psb_move_alloc(ov_el,desc%ovrlap_elem,info)
 
+    l_ov_ix = l_ov_ix+3  
+
+    if (debug_level >= psb_debug_inner_) &
+         & write(debug_unit,*) me,' ',trim(name),': Ov len',l_ov_ix,l_ov_el
 
-  call psb_erractionrestore(err_act)
-  return
+    allocate(ov_idx(l_ov_ix),ov_el(l_ov_el,3), stat=info)
+    if (info /= psb_no_err_) then
+      info=psb_err_from_subroutine_
+      err=info
+      call psb_errpush(err,name,a_err='psb_realloc')
+      goto 9999
+    end if
+
+    l_ov_ix=0
+    l_ov_el=0
+    i = 1
+    do while (iv(i) /= -1) 
+      idx = iv(i)
+      i   = i+1
+      nprocs = iv(i)
+      l_ov_el          = l_ov_el+1
+      ov_el(l_ov_el,1) = idx                    ! Index
+      ov_el(l_ov_el,2) = nprocs                 ! How many procs
+      ov_el(l_ov_el,3) = minval(iv(i+1:i+nprocs))  ! master proc
+      do j=1, nprocs
+        if (iv(i+j) /= me) then
+          ov_idx(l_ov_ix+1) = iv(i+j)
+          ov_idx(l_ov_ix+2) = 1
+          ov_idx(l_ov_ix+3) = idx
+          l_ov_ix = l_ov_ix+3
+        endif
+      enddo
+      i = i + nprocs + 1
+    enddo
+    l_ov_ix         = l_ov_ix + 1
+    ov_idx(l_ov_ix) = -1
+    call psb_move_alloc(ov_idx,desc%ovrlap_index,info) 
+    if (info == psb_success_) call psb_move_alloc(ov_el,desc%ovrlap_elem,info)
+
+
+    call psb_erractionrestore(err_act)
+    return
 
 9999 call psb_error_handler(ictxt,err_act)
 
     return
 
-end subroutine psi_bld_tmpovrl
+  end subroutine psi_bld_tmpovrl
+
+end submodule psi_bld_tmpovrl_impl_mod
diff --git a/base/internals/psi_crea_bnd_elem.f90 b/base/internals/psi_crea_bnd_elem.f90
index 6549f7f2..32a671fc 100644
--- a/base/internals/psi_crea_bnd_elem.f90
+++ b/base/internals/psi_crea_bnd_elem.f90
@@ -43,77 +43,80 @@
 !    desc_a   - type(psb_desc_type).    The communication descriptor.        
 !    info     - integer.                  return code.
 ! 
-subroutine psi_crea_bnd_elem(bndel,desc_a,info)
-  use psi_mod, psb_protect_name => psi_crea_bnd_elem
-  use psb_realloc_mod
-  use psb_desc_mod
-  use psb_error_mod
-  use psb_serial_mod
-  implicit none
-  
-  integer(psb_ipk_), allocatable :: bndel(:)
-  type(psb_desc_type), intent(in)  :: desc_a
-  integer(psb_ipk_), intent(out) :: info
+submodule (psi_i_mod) psi_crea_bnd_elem_impl_mod
 
-  integer(psb_ipk_), allocatable :: work(:)
-  integer(psb_ipk_) :: i, j, nr, ns, k, err_act
-  character(len=20)    :: name
+contains
+  subroutine psi_crea_bnd_elem(bndel,desc_a,info)
+    use psb_realloc_mod
+    use psb_desc_mod
+    use psb_error_mod
+    use psb_serial_mod
+    implicit none
 
-  info = psb_success_
-  name='psi_crea_bnd_elem'
-  call psb_erractionsave(err_act)
+    integer(psb_ipk_), allocatable :: bndel(:)
+    type(psb_desc_type), intent(in)  :: desc_a
+    integer(psb_ipk_), intent(out) :: info
 
-  allocate(work(size(desc_a%halo_index)),stat=info)
-  if (info /= psb_success_ ) then 
-    info = psb_err_alloc_dealloc_
-    call psb_errpush(info,name)
-    goto 9999
-  end if
+    integer(psb_ipk_), allocatable :: work(:)
+    integer(psb_ipk_) :: i, j, nr, ns, k, err_act
+    character(len=20)    :: name
 
-  i=0
-  j=1
-  do while(desc_a%halo_index(j) /= -1) 
+    info = psb_success_
+    name='psi_crea_bnd_elem'
+    call psb_erractionsave(err_act)
 
-    nr = desc_a%halo_index(j+1)
-    ns = desc_a%halo_index(j+1+nr+1)
-    do k=1, ns
-      i = i + 1
-      work(i) = desc_a%halo_index(j+1+nr+1+k)
+    allocate(work(size(desc_a%halo_index)),stat=info)
+    if (info /= psb_success_ ) then 
+      info = psb_err_alloc_dealloc_
+      call psb_errpush(info,name)
+      goto 9999
+    end if
+
+    i=0
+    j=1
+    do while(desc_a%halo_index(j) /= -1) 
+
+      nr = desc_a%halo_index(j+1)
+      ns = desc_a%halo_index(j+1+nr+1)
+      do k=1, ns
+        i = i + 1
+        work(i) = desc_a%halo_index(j+1+nr+1+k)
+      enddo
+      j  = j + 1 + ns + 1 + nr + 1
     enddo
-    j  = j + 1 + ns + 1 + nr + 1
-  enddo
 
-  call psb_msort_unique(work(1:i),j)
+    call psb_msort_unique(work(1:i),j)
 
-  if (.true.) then 
-    if (j>=0) then 
-      call psb_realloc(j,bndel,info)
+    if (.true.) then 
+      if (j>=0) then 
+        call psb_realloc(j,bndel,info)
+        if (info /= psb_success_) then 
+          call psb_errpush(psb_err_from_subroutine_,name,a_err='Allocate')
+          goto 9999      
+        end if
+        bndel(1:j) = work(1:j)
+      else
+        if (allocated(bndel)) then 
+          deallocate(bndel)
+        end if
+      end if
+    else
+      call psb_realloc(j+1,bndel,info)
       if (info /= psb_success_) then 
         call psb_errpush(psb_err_from_subroutine_,name,a_err='Allocate')
         goto 9999      
       end if
       bndel(1:j) = work(1:j)
-    else
-      if (allocated(bndel)) then 
-        deallocate(bndel)
-      end if
-    end if
-  else
-    call psb_realloc(j+1,bndel,info)
-    if (info /= psb_success_) then 
-      call psb_errpush(psb_err_from_subroutine_,name,a_err='Allocate')
-      goto 9999      
-    end if
-    bndel(1:j) = work(1:j)
-    bndel(j+1) = -1
-  endif
+      bndel(j+1) = -1
+    endif
 
-  deallocate(work)
-  call psb_erractionrestore(err_act)
-  return
+    deallocate(work)
+    call psb_erractionrestore(err_act)
+    return
 
 9999 call psb_error_handler(err_act)
 
-  return
+    return
 
-end subroutine psi_crea_bnd_elem
+  end subroutine psi_crea_bnd_elem
+end submodule psi_crea_bnd_elem_impl_mod