function PRE_fill_envelope_rhs(rhs) return 0 end function POST_fill_envelope_rhs(rhs) return 0 end function PRE_fill_envelope_lhs(rhs) return 0 end function POST_fill_envelope_lhs(rhs) return 0 end function PRE_fill_spec_rhs(rhs) return 0 end function POST_fill_spec_rhs(rhs) return 0 end function PRE_fill_spec_lhs(rhs) return 0 end function POST_fill_spec_lhs(rhs) return 0 end