def openTypeHheaCaretSlopeRiseFallback(info):
    """
    Fallback to *openTypeHheaCaretSlopeRise*. If the italicAngle is zero,
    return 1. If italicAngle is non-zero, compute the slope rise from the
    complementary openTypeHheaCaretSlopeRun, if the latter is defined.
    Else, default to an arbitrary fixed reference point (1000).
    """
    italicAngle = getAttrWithFallback(info, "italicAngle")
    if italicAngle != 0:
        if (hasattr(info, "openTypeHheaCaretSlopeRun") and
                info.openTypeHheaCaretSlopeRun is not None):
            slopeRun = info.openTypeHheaCaretSlopeRun
            return otRound(slopeRun / math.tan(math.radians(-italicAngle)))
        else:
            return 1000  # just an arbitrary non-zero reference point
    return 1