NOTICE DATE: September 17, 2009

NOTICE TYPE: W-A091709-01 Maintenance Outage – NMMS

SHORT DESCRIPTION: Scheduled Maintenance Outage of the Network Model Management System (NMMS)

INTENDED AUDIENCE: TDSPs / TSPs

DAY AFFECTED: Saturday, September 26, 2009, 3:30 PM – 4:30 PM

LONG DESCRIPTION: NMMS will undergo an outage from 3:30 PM until 4:30 PM on Saturday, September 26, 2009. The Network Model Management System, currently supporting the Single Entry Model, will be inaccessible due to failover testing on the Citrix servers. The outage is expected to last less than one hour.

A subsequent notice will be sent if the maintenance period, for unforeseen reasons, exceeds the communicated end time.

CONTACT: If you have any questions, please forward them to [log in to unmask] or contact your ERCOT Account Manager. You may also call the general ERCOT Client Services phone number at (512) 248-3900 or contact ERCOT Client Services via email at [log in to unmask].

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