anchor.diff:      integer(c_long),allocatable::oid(:) !< octal ids
       integer,allocatable::lvl(:) !< tree levels
       integer,allocatable::neib(:,:) !< neighbor lists
  +    integer,allocatable::flag(:) !< flag (0-out, 1-in, 2-cut)
     contains
       procedure,public::init=>initOtGrid
       procedure,public::clear=>clearOtGrid
  
positive.code:     allocate(this%oid(this%nC))
      allocate(this%lvl(this%nC))
      allocate(this%neib(N_FACE,this%nC))
      call ot_genConn(this%otree,this%oid,this%lvl,this%neib)
    end subroutine
    
    !> clear this otGrid
  
negative.code:     if(allocated(this%oid)) deallocate(this%oid)
      if(allocated(this%lvl)) deallocate(this%lvl)
      if(allocated(this%neib)) deallocate(this%neib)
      if(allocated(this%flag)) deallocate(this%flag)
    end subroutine
    
    !> position of cell k
  