def paz_to_sacpz_string(paz, instrument_sensitivity):
    """
    Returns SACPZ ASCII text representation of Response.

    :type paz: :class:`PolesZerosResponseStage`
    :param paz: Poles and Zeros response information
    :type instrument_sensitivity: :class:`InstrumentSensitivity`
    :param paz: Overall instrument sensitivity of response
    :rtype: str
    :returns: Textual SACPZ representation of poles and zeros response stage.
    """
    out = []
    out.append('ZEROS %i' % len(paz.zeros))
    for c in paz.zeros:
        out.append(' %+.6e %+.6e' % (c.real, c.imag))
    out.append('POLES %i' % len(paz.poles))
    for c in paz.poles:
        out.append(' %+.6e %+.6e' % (c.real, c.imag))
    constant = paz.normalization_factor * instrument_sensitivity.value
    out.append('CONSTANT %.6e' % constant)
    return '\n'.join(out)
