Rockwell Automation FactoryTalk Historian SE DataLink 4.2 User Guide - Manual (Page 29)

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Instead, only the results that fit within the specified array dimensions are
displayed.
Time Arguments
Many FactoryTalk Historian DataLink functions require Start Time and
End Time arguments to retrieve an array of event values over a specific
time range. Follow these guidelines when specifying time arguments:
 Time strings may be entered directly in edit fields in either absolute or
relative FactoryTalk Historian time (page 86) formats (for example,
10-Dec-99 19:12 or -3h).
 If the start time is more recent than the end time, results are displayed
in reverse chronological order.
 Time stamps referenced in spreadsheet cells may also use fixed or
relative FactoryTalk Historian time formats, and should be preceded
by an apostrophe to indicate a string (for example, '10-Dec-99
19:12 or '-3h).
 Cell references may also use the absolute Excel time format (such as
39299.6146, equivalent to 8/5/2007 2:45:00 PM). Excel
stores time stamps in this format, which represents the cumulative
number of days since 1900. Excel can display the same time stamps
using any date-time format assigned to the cell.
 Some arguments call for an interval or duration of time, represented by
a single value rather than start and end times. Whether referenced or
entered directly, interval values should use relative FactoryTalk
Historian time strings such as a number followed by a time variable
(for example, 1d or 30m), and may not specify or refer to a fixed
FactoryTalk Historian or Excel time stamp. For example, to specify an
interval of 32 minutes, enter or reference a cell containing the string
32m.