ART'S LIABILITY FOR OUTAGES. All liability of ART for interruptions, errors, omissions, Outages or defects occurring in the course of furnishing the Services and not caused by actions of Purchaser or third parties shall be strictly limited to Outage credits against sums paid or to be paid in an amount determined in accordance with Section 12.2 ("CREDIT"). Credit for Outages shall be allowed only when Outages are caused by or occur in the facilities or the Services provided by, operated or serviced by ART. No Credit shall be allowed for Outages due to the failure of facilities, services or equipment not provided, operated or serviced by ART or the acts or omissions of Purchaser or third parties. No Credit shall be given for any Outages caused by testing or emergency interruptions, or by routine maintenance provided that ART has given Purchaser advance notice of such maintenance. Purchaser must promptly Notify ART of any Outages and include details of such Outages, including, without limitation, time the Outage occurred, duration and cause, if known.