def to_spec(self):
        rel_instr_specs = []
        for rel_instr in self._relative_instructions:
            rel_instr_spec = rel_instr.splitname
            if rel_instr.from_ is not None or rel_instr.to is not None:
                from_ = rel_instr.from_
                to = rel_instr.to
                unit = rel_instr.unit
                rounding = rel_instr.rounding
                unit = unit if unit == "%" else ""
                from_ = str(from_) + unit if from_ is not None else ""
                to = str(to) + unit if to is not None else ""
                slice_str = f"[{from_}:{to}]"
                rounding_str = (
                    f"({rounding})" if unit == "%" and rounding is not None and rounding != "closest" else ""
                )
                rel_instr_spec += slice_str + rounding_str
            rel_instr_specs.append(rel_instr_spec)
        return "+".join(rel_instr_specs)