OLE Automation Date
From Just Solve the File Format Problem
OLE Automation Date is one of the date/time formats used with Microsoft's OLE Automation API. It may be used in OLE Property Sets, for example.
It is also be known as OLEAUT date, VARIANT DATE, variant time, VT_DATE, etc.
Format details
It is in the form of an 8-byte floating point number.
Positive values correspond to the number of days (including fractions of a day) since "midnight 1899-12-30". Apparently this means the midnight at the beginning of 1899-12-30, i.e. 48 hours before the beginning of the year 1900.
Negative values are interpreted in a more complex way.
The valid range is usually considered to be the years 100 through 9999.
Times are usually treated as being in local time.