The key changes made from the draft Guideline of 20 July 2009 are: the impact that legal operating requirements (eg. environmental limits) can have on minimum operating levels has been recognised the requirement to include an estimate of the duration of a below minimum ramp rate or inflexibility has been removed if this information is inherent in other data provided with the offer or rebid in situations where a rebid is submitted in response to a series of events, the 'most significant’ of the series must be provided in the rebid reason, replacing the ‘first event’ that was included in the draft Guideline ramp rates in offers and rebids need only be brought into line with Supervisory Control And Data Acquisition (SCADA) ramp rate values in circumstances where dispatch would be impacted minor wording change to clarify that when a ramp rate is rebid, it only has effect from the next dispatch interval.