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

The NYISO is reserving hours-beginning 6 and 10 in the 14 July 2001
real-time market to verify prices.
Prices in the 15 July 2001 Day-Ahead market are correct.
Pursuant to ECA-B the NYISO is reserving the following hours at the
following external proxy buses:
HQ: 02:00, 10:00, 23:00
NE: 02:00, 10:00, 23:00
OH: 02:00, 10:00, 23:00
PJM: 02:00, 10:00, 23:00