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 is used in some OLE Property Sets, for example.
It is also known as OLEAUT date, VARIANT DATE, variant time, VT_DATE, etc.
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.