Siemens SIMATIC PCS 7 Function Manual page 53

Keyword
NOW = current local time of the server
SECOND = current second
MINUTE = current minute
HOUR = current hour
DAY = current day
WEEK = current week
MONTH = current month (0-11)
YEAR = current year
Offset
+/-S = deviation in seconds
+/-M = deviation in minutes
+/-H = deviation in hours
+/-D = deviation in days
+/-W = deviation in weeks
+/-MO = deviation in months
+/-Y = deviation in years
Example
DAY - 1D = previous day
DAY-1D + 7H30 = previous day at 7:30 a.m.
MO-1D+5H = last day of the previous month at 5.00 a.m.
NOW-1H15M = 1 hour and 15 minutes ago
YEAR+3MO= April of this year
OpenPCS 7
Function Manual, 05/2012, A5E02780178-02
6.4 OPC Historical Data Access (OPC HDA)
OpenPCS 7 interface
53