JSavitt@nyiso.com writes to the NYISO_TECH_EXCHANGE Discussion List:

The NYISO is reserving hours-beginning 1 and 7 in the 19 August 2001
real-time market to verify prices.
The prices in the 20 August 2001 Day-Ahead Market are correct.
Pursuant to ECA-B the NYISO is reserving the following hours at the
following external proxy buses:
HQ: 0:00-9:00, 21:00
NE:  0:00-1:00, 4:00-5:00, 21:00
OH: 0:00-1:00, 4:00-5:00, 21:00
PJM:  0:00-1:00, 4:00-5:00, 21:00